This guide explains how to transfer to Infomaniak data (Web, Mail, Domain, and even Cloud) currently hosted elsewhere. You obviously remain the owner of your data, without any loss or interruption!

Specific guides

Click on the link corresponding to your current host:

• Swisscom: complete guide to migrate Web, Mail and domain name

Guides for any other hoster

To retrieve any other data, follow the procedures below:

1. Guide to copy Web data (all PHP, HTML sites, etc. - for WordPress refer to this other guide)
    
2. Guide to copy Mail data (email addresses, mailbox content, etc.)
    
3. Guide to transfer the domain name (domain management, DNS zone, etc.)
    

You can also bring other types of data to the Infomaniak servers:

• Dropbox, Google Drive, etc. content: refer to this other guide
• Data on NAS Synology or QNAP: refer to this other guide

Why join Infomaniak?

By grouping your domain names, websites, and email addresses with Infomaniak, you simplify the management of your invoices and services. Moreover, your domains will automatically link with your site and email address. You will therefore not need to manually configure the DNS of your domains with another registrar.

Learn more about Infomaniak

• Infomaniak, the Ethical Cloud
• Infomaniak's eco-responsible approach

This guide helps you identify and correct errors encountered when attempting to use your email software/client such as Microsoft Outlook, Mozilla Thunderbird, Apple Mail, etc.

Always use…

• the single server name: mail.infomaniak.com (for IMAP reception and SMTP sending servers)
• the correct incoming/outgoing port numbers
• Authentication in the settings when it is offered, and if necessary, enter the username (your full email address) and password in the fields related to mandatory authentication
• the correct email password which is usually different from the username used to log in to Infomaniak (click here to check that you are using the correct password and if necessary, change the password of your email address) - beware of the sign $
• an existing email address that must have been actually created (or set as an alias)
• one protocol at a time (never check an email box with devices configured in POP3 for some and in IMAP for others because these two protocols do not work well together)

You must try to...

• compare the recommended settings for the email software/client used, especially if you have recently changed the password on the Infomaniak side
• check your emails using a different network (WiFi, mobile hotspot from 4G/5G, or any other internet connection)
• temporarily disable your security applications (antivirus, firewall, VPN...); if you can then retrieve your emails normally, contact the publisher of the security application(s) you are using
• type your password in plain text in a word processor; depending on your keyboard configuration, the key A may correspond to the letter Z and the key Q may refer to the letter A...
• Restart and try sending/receiving again: some applications require validating the configuration parameters window several times or need to be restarted to apply their new settings
• compose a new message after modifying your settings: a message in the process of being drafted that would be saved in the Drafts folder may not take into account any configuration changes

The types of errors

• 0x800... - refer to this other guide
• Certificate error (SSL or other): refer to this other guide
• 550 5.7.1 relaying denied or Proper authentication required - refer to this other guide
• 535 5.7.0 authentication failed - refer to this other guide

also:

• "573 Antispam: Authentication not possible. Please use port 587 instead of port 25."
  or "An operation on the server timed out. The server may be down, overloaded, or there may be too much net traffic."
  or "The time limit has expired" with an error number following (421, or 573 for example).
  Most ISPs (Internet Service Providers) have blocked the SMTP sending port n°25 for many years now. Therefore you should never specify port 25 as the SMTP port. To still be able to send emails, use the recommended ports.

This guide explains how to provide useful details when requesting assistance and authorize Infomaniak Support to access your online products and more specifically their content.

Preamble

• To analyze the service behavior and identify the source of the issue you are experiencing, Support Infomaniak may ask you to perform an action to grant temporary access to part of your content, strictly limited to this analysis context, to save time in diagnosing and avoiding unnecessary back-and-forth; in accordance with Infomaniak's privacy policy, no data will be used for other purposes.
• Only Infomaniak employees who will handle your support request will be able to access it from Infomaniak's controlled facilities.
• You can revoke this access at any time or wait 7 days for it to expire automatically.
• Various contents may be accessible (read below): authorizing access to one does not authorize access to the other - these are specific authorizations.
• You can also easily share a specific email.

Allow Support to access your content

In this regard, to allow Infomaniak to access a specific part of your services:

1. Click here to access the management of Support access to your products on the Infomaniak Manager (need help?).
2. Click on the toggle switch to allow access to the content of…
   1. … email addresses linked to the Web app Mail Infomaniak (online service mail.infomaniak.com).
   2. … folders among the existing kDrive(s) in the organizations to which the current user belongs
   3. … discussions among the kChat products existing in the Organizations to which the current user belongs
      

Take screenshots…

… on Windows

Microsoft offers a software pre-installed for screenshots. But to do them manually:

1. Display what you want/need to transmit on the screen.
2. Press the PRINTSCREEN key on your keyboard (or PRTSCR, IMPR. ECRAN, etc.) once.
3. In Microsoft Word (or similar), go to "Edit" -> "Paste" to place your image on the page.
4. Save your file.
5. Repeat the operation from step 1 to step 5 as many times as the number of desired captures.

… on macOS

1. Press the "CMD" + "shift" (the upward-facing arrow — shift) + "3" keys simultaneously.
2. Every time you press these keys, an image file is created on your computer's desktop.

... on iOS (iPhone, iPad...)

1. Press the "Power" + "Home" buttons (the only two physical buttons) simultaneously.
2. Retrieve the screenshots in the "Photos" app on your device.

... on Android (for example Samsung, LG or Huawei)

1. Press the “Volume Down” button (on the side) and the lock button at the same time.
2. The captured image is automatically saved in a Screenshots folder in the gallery.

Popup Windows

To copy and paste an error message from a Windows popup as text, simply press the CTRL + C key on your keyboard to copy the message to the clipboard. You can then paste it (CTRL + V) into the body of the message you send to us.

Browser JavaScript console…

... on Windows

Chrome, Firefox and Safari: enter the key combination CTRL + SHIFT + i
Internet Explorer and Edge: press the F12 key

... on macOS

Chrome: enter the key combination ⌘ + ⌥ + J
Safari: enter the key combination ⌘ + ⌥ + C

1. Then, click on the crossed-out circle icon or similar to reset the log.
2. Display the page of your site that is experiencing the issue.
3. The console tab displays JavaScript errors and missing online resources.

This guide explains how to recover recently lost emails, especially in case of accidental deletion by the user.

Preamble

• Infomaniak backs up the content of each email address once a day (usually early in the morning).
• It is therefore possible to restore the mailbox to its state on the day of the backup.
• ELEMENTS RECOVERED:‍
  • Emails no longer existing at the time of the restoration request will be returned to their original location.
  • Certain settings related to your email address (the "answering machine" section and the "redirection" section, among others) will also be restored if they have changed in the meantime.
• ELEMENTS NOT RECOVERED:‍
  • Moved but not deleted emails may not reappear in the expected location since they still exist somewhere in the email account's folder structure - you need to search for them.
  • The backup restoration does not include the calendar or the address book.
  • Emails that were not yet present or no longer existed at the time of the daily backup (also see the POP3 chapter below); example: an email received at 8 am, deleted at 9 am while the backup took place at 5 am.
• ELEMENTS NOT MODIFIED:‍
  • Emails received, created and stored in various folders (such as sent messages) during the interval (between the date you want to go back to and the date you perform the restoration) are not affected, they remain present.

Backup retention period

Once a full backup of your mailbox has been completed, Infomaniak makes it available to you for a certain number of days depending on your offer:

• my kSuite = 7‍ | my kSuite+ = 30‍
• kSuite Standard 1 max. user = 30‍ | kSuite Standard 2 min. users = 30‍ | kSuite Pro = 30‍ | kSuite Entreprise = 30‍
• Service Mail Starter = 7‍ | Service Mail 5 addresses min. = 7‍

By upgrading to a my kSuite offer, it is possible to recover a backup up to 30 days even if the 7 days have passed at the time of the upgrade.

Also refer to this other guide regarding the storage limits of your messages.

Restore from the Infomaniak Web Mail app

Prerequisites

• Ensure that the deletion occurred less than 7 days ago (or within the timeframe included with your offer - see above).
• Have permission to manage backups: if you had been invited to the Web app Mail Infomaniak (online service mail.infomaniak.com) to manage your address, it is possible that the Service Mail manager has revoked this right from their admin account.

To restore emails:

1. Click here to access the Web app Mail Infomaniak (online service mail.infomaniak.com).
2. Check or select the email address in question from the dropdown menu on the left sidebar.
3. Click on Advanced actions.
4. Click on Restore:
5. Choose a Restoration date.
6. Click on Restore emails.
7. Once the restoration is complete, an informational email is sent.

Restore from Mail Service

Prerequisites

• To be Administrator or Legal Representative‍ within the Organization that manages the Mail service.
• Ensure that the deletion occurred less than 7 days ago (or within the timeframe included with your offer - see above).

To restore emails from a Mail service:

1. Click here to access your product management on the Infomaniak Manager (need help?).
2. Click directly on the name assigned to the relevant product.
3. Click on the email address concerned in the table that appears.
4. Click on the Actions on the address button at the top right.
5. Click on Restore emails:
   
6. Choose a Restoration date.
7. Click on Restore emails.
8. Once the restoration is complete, an informational email is sent to you.

Emails stored in non-conventional folders

If you store your messages in unusually named folders (for example, folders named Corbeille or Spam) please refer to the important information in this other guide on the subject.

Users of email software/client configured in POP3

If you usually check your email with a software/email client like Outlook and it is configured with the POP / POP3 protocol, it will not be possible to restore everything since the backup is done once a day, it only keeps the messages that were at the time of the backup in the Infomaniak inbox; the same applies to your other folders (Sent Messages for example) present in the POP3 application: these are not synchronized with Infomaniak and therefore are not backed up; it is therefore better to prefer the IMAP protocol in your software/email client in the future.

This guide helps you find solutions if you send an email from an address hosted by Infomaniak and the message ends up in the Spam folder (junk mail) of your recipient.

Using email effectively

Infomaniak stands out among the leading providers in the market thanks to enhanced systems ensuring the security and good deliverability of emails. As long as the basic rules are also respected on your side, there is little risk of seeing your message end up in the recipient's junk mail. To do this:

1. Use a valid email address

Ensure that your email address and its domain are correct and valid; check the security parameters of your domain. If you correct a parameter, wait 24 hours before trying to send again.

2. Avoid suspicious content

Whether in the subject line or the body of the email, avoid using words or phrases often associated with spam, generic messages, overly complex layouts, and unsafe or poorly formatted internet links. Personalizing an email by using the recipient's name enhances the legitimacy of your messages.

Sending suspicious attachments or large files can lead to the Spam folder; use SwissTransfer for example.

3. Test sending from the Infomaniak Web Mail app

If you send your messages from an email software/client, try using the Web app **Mail** Infomaniak (online service mail.infomaniak.com) to compare the results and more precisely identify the source of the spam issue.

4. Reputation of the custom domain

If you send emails from an address @domain.xyz and for some reason this domain has recently acquired a " bad reputation", your email will be impacted and may be considered Spam by different providers. You need to address the reasons that led to the depreciation of your domain name.

5. Obtain consent

Make sure you know the person you are writing to or at least send to a user likely to expect your message so that they do not mark it as Spam. For grouped and/or regular sends, voluntary subscriptions reduce the risks of being classified as spam; also consider the Newsletter Infomaniak solution.

6. Optimize the sending frequency

An excessive volume of emails sent to multiple recipients of the same provider may be considered spam. Respect a reasonable frequency when sending your emails.

7. Get added to Infomaniak's whitelist

If you regularly send emails to a recipient also hosted by Infomaniak, and your messages are suddenly considered Spam, your contact can add your email address to the whitelist to allow your mail to reach their normal inbox. However, it is important to pay attention to the reasons that led your messages to spam, as not everyone will be able to whitelist your address.

This guide explains how…

• … activate incoming mail filtering
• … automatically sort promotional messages
• … report certain fraudulent messages

… to reduce unwanted or excessive messages on an email address managed by Infomaniak.

Solutions to exclude, sort, and filter incoming emails

Automatic filtering methods

• Refer to this guide to use the folder by activating the spam filter (it can be deactivated).
• Refer to this guide to use the and folders by activating the advertising & social networks filter.

Manual methods

• Refer to this guide to report an incoming message that was not detected as spam (advertisement / unsolicited contact).
• Refer to this guide to report an incoming message that was not detected as phishing (fraud / deceptive fake email).
• Refer to this guide to block or allow specific email addresses or even entire domains.
• Refer to this guide to define your own sorting and classification filters ('Sieve language') for incoming mail…
  • … this will allow you to filter messages sent to a temporary alias that you can create to protect yourself when registering on the Internet, for example.

If you are facing a wave of spam or unusual messages, refer to this other guide to perform some checks.

If your own sent messages are often mistakenly classified as spam, refer to this guide to perform some checks.

This guide details the various identifiers that you will use with Infomaniak, and what happens if one of the passwords is changed.

Preamble

1. As is the case with many other online services, you identified yourself with Infomaniak upon registration using a personal email address.
2. This personal email address serves as your login identifier when you want to connect to Infomaniak services.
3. This login identifier has its own password (which you chose when creating your Infomaniak user account - your personal email address, see above).

There is no connection between…

• … this identifier/password pair described in points 1/2/3 above…
• … and the email addresses that you have created or obtained subsequently with Infomaniak.

There could be only one connection if the spelling is the same (for example, you signed up with the email address toto@abc.xyz and you manage the email address toto@abc.xyz with Infomaniak) but even in this case, the password will very likely be different, once for the login identifier toto@abc.xyz and once for the email address toto@abc.xyz.

When should you specify…

… the login ID?

• Whether it's on mail.infomaniak.com or the Infomaniak Mail app, it is essential to log in with…
  • … the identifier for your Infomaniak user account…
  • … and its password.
• ⚠️ This will NOT work by entering an email address and its password directly (if no user account exists with the same spelling and password).

… the email address?

• In an email software/client (like Microsoft Outlook, Apple Mail, etc.) you must enter…
  • … the email address you wish to access…
  • … and its password.
• ⚠️ This will NOT work by entering the password you use to log in to the Infomaniak interface, as this password is very likely different!

Troubleshoot a connection issue

There is no need to contact Infomaniak Support (which does not have any of your passwords) if…

1. … you fail to log in to interfaces such as mail.infomaniak.com or manager.infomaniak.com due to an incorrect password…
   1. The only solution is the reset of the login password.
2. … you are unable to connect your email address to your email software/client (such as Microsoft Outlook, Apple Mail, etc.) due to an incorrect password:
   1. Test the email address / password combination to check if an error is mentioned.
   2. Reset the email password if necessary.

To remember

In summary, you have:

• 1 identifier (in the form of an email address) and 1 password to access…
  • … to Mail https://mail.infomaniak.com
  • … to Manager https://manager.infomaniak.com
• 1 password for each email address hosted at Infomaniak

These two pieces of information may be identical or not, depending on your choice. And if you change one, it will not necessarily change the other unless they have been unified (this will be specified - read below).

In which case are the passwords unified?

Suppose that within the Mail Service that you own in your Infomaniak account, you create an email address named julie@entreprise-familiale.xyz (password 123-Abc).

If then an Infomaniak account…

• … is created with the same name (julie@entreprise-familiale.xyz - password does not matter)…
• … is the only account to access the email address julie@entreprise-familiale.xyz via mail.infomaniak.com…
• … has sufficient permissions to change the email password…

… then the password unification will be offered when you go through the process of changing the email password from the Infomaniak account in question.

And the other credentials?

Acquiring other Infomaniak products involves obtaining other credentials such as those for FTP, MySQL, SSH, WebDAV connections, etc. but they are entirely independent of the 2 types of credentials described above.

Thank you for entrusting your email hosting to Infomaniak.

This guide allows you to quickly use the essential functions of your new Mail Service. In case of any issues, consult the knowledge base before contacting Infomaniak support.

Create email addresses

• Get started with the interface
• Create email addresses
• Create email addresses in bulk
• Create email addresses that serve only as redirects
• Copy the mail content from Gmail, OVH, etc. to Infomaniak

Use your created email addresses

• Synchronize your devices
• Check the log of incoming and outgoing emails
• Hide the recipient addresses of an email
• Discover the Infomaniak Mail mobile app
• Use the email service even if the domain points to Wix or similar
• Use the email service with your website
• Use the email drafting assistant

Get acquainted with important information

• Sending limits
• Size limits
• Recipient limit
• The various identifiers
• Troubleshoot an error with an email software/client

Customize your email

• Add a signature
• Add an alias
• Add an out-of-office message
• Add a domain name
• Automatically sort incoming emails

Secure your email address

• Filtering solutions guide
• Manage security alerts
• Change the password of an email address
• Manage SPF, DKIM, DMARC, etc.
• Report a phishing email

This guide explains which protocols and ports can be used with Infomaniak's email services (Service Mail in particular).

Mandatory ports and parameters

When this is requested during a software or email application configuration, use only these parameters:

If you specify other indications, email errors may occur.

Other supported but not recommended protocols

• port 143 (standard port for receiving messages via IMAP)
• port 110 (standard port for receiving messages via POP3)‍
• port 995 (secure port for receiving messages via POP3s)
• port 587 (alternative port not recommended for sending messages via SMTP)
• TLS authentication on SMTP ports 587 and 25
• STARTTLS authentication for IMAP, POP3 and SMTP
• SMTP authentication (either LOGIN or PLAIN)

The Infomaniak API does not offer any email connection as IMAP and SMTP are the "APIs"; to this end, use a Python library such as https://docs.python.org/3/library/email.examples.html and https://docs.python.org/3/library/imaplib.html or any library using IMAP and SMTP.

To display emails from php:
imap_open("{mail.infomaniak.com:993/imap/ssl}", $email, $password);

The MTA-STS mechanism is not implemented or verified, Infomaniak using instead DANE which guarantees an encrypted connection under these conditions:

• The client sends an e-mail to a domain that has DANE.
• The client receives an email from an SMTP server that uses DANE.
• In all other cases, it will be a random connection that does not guarantee 100% that the connection will be encrypted.

This guide helps you identify and correct most email errors encountered after sending an email to a recipient. Refer to this other guide if you are looking for information about errors obtained when configuring an email address in a software/email client.

Introduction

• Generally, a mail error message is the result of…
  • … an incorrect configuration of the domain name used with your email,
  • … an issue with your recipient's (mail provider).
• In any case, a delivery failure report (Mailer Daemon or Mail Delivery Subsystem) containing the explanation is sent to the sender.

Searching for and identifying the email error

When your message does not reach your recipient, an initial failure report (Temporary Delivery Failure Report) is sent and specifies that the server will attempt to resend your message several times.

A final delivery failure report (Final Delivery Failure Report or Undeliverable Mail) issued by the recipient's server is sent to the sender (via a passage through the Infomaniak mail server, hence the mention of Infomaniak at the beginning of most error messages you may receive) to inform them that the email could not be delivered even after several attempts.

The notification always contains the reason for the failure. Example below:

This is the mail system at host smtp-1-1234.mail.infomaniak.ch.
I'm sorry to have to inform you that your message could not be delivered to one or more recipients. It's attached below.
For further assistance, please send mail to postmaster.
If you do so, please include this problem report. You can delete your own text from the attached returned message.
The mail system anna.a@abc.xyz: host mxbw-abc-xyz.abc-ab12.abc.ch[123.456.789.00] said: 550 5.1.1
anna.a@abc.xyz recipient rejected, account administratively disabled (in reply to RCPT TO command) 

So here the address of your recipient is visibly suspended by their email provider (account administratively disabled).

Sometimes you need to look for the reason for the error message received among its attachments (often a raw text file). Example:

Reporting-MTA: dns; mxbw.abc.ch‍ [123.456.789.00]
Received-From-MTA: dns; smtp-1-1234.mail.infomaniak.ch [12.345.678.99]
Arrival-Date: Tue, 01 Aug 2023 15:49:22 +0200
Final-recipient: rfc822; anna.a@abc.xyz
Diagnostic-Code: smtp; 552 RCPT TO:anna.a@abc.xyz‍ Mailbox disk quota exceeded
Last-attempt-Date: Tue, 01 Aug 2023 15:49:22 +0200

Here the mailbox of your correspondent external to Infomaniak seems to be full (Mailbox disk quota exceeded).

Most common cases

SPF Failure

The SPF (Sender Policy Framework) record is not correctly configured:

Subject: Delivery Status Notification (Failure)
From: Mail Delivery System mailer-daemon@domain.xyz
To: Anna.A anna.a@abc.xyz
This is an automatically generated Delivery Status Notification.
Delivery to the following recipient failed due to SPF failure:
anna.a@abc.xyz
Technical details of SPF failure:
The sender's domain domain.xyz does not have a valid SPF record. Please contact your email administrator to correct the SPF configuration.

Solution: check the configuration of your domain name and especially the SPF record if your website is hosted with Wix or another provider.

User Unknown

The email address specified in the message is invalid or does not exist:

Subject: Delivery Status Notification (Failure)
From: Mail Delivery System mailer-daemon@domain.xyz
To: Anna.A anna.a@abc.xyz
This is an automatically generated Delivery Status Notification.
Delivery to the following recipient failed permanently:
anna.a@abc.xyz
Technical details of permanent failure:
The email address does not exist. Please check the recipient's email address and try again.

Solution: carefully check the recipient's email address and correct it if necessary; ensure that you are using a valid email address for the recipient.

Temporary Failure

Le serveur de messagerie du destinataire rencontre des problèmes temporaires ou est indisponible.

Solution: wait for some time, then try sending the message again later. If the problem persists, contact the recipient's technical support for help.

Blocked by SPAM Filter (or Content Rejected)

The recipient's mail server has blocked the message due to anti-spam filtering rules:

Subject: Delivery Status Notification (Failure)
From: Mail Delivery System mailer-daemon@domain.xyz
To: Anna.A anna.a@domain.xyz
This is an automatically generated Delivery Status Notification.
Delivery to the following recipient failed due to the message being rejected as spam:
anna.a@domain.xyz
Technical details of delivery failure:
The content of the message triggered the spam filters of the recipient's email server. Please review the message content and try again.

Solution: check if your message contains elements that may be considered spam (keywords, suspicious links, etc.). Contact the recipient to check if the message has been filtered into the junk mail folder.

Refer to this other guide regarding outgoing spam and this other guide regarding incoming spam.

Bad Reputation

The recipient's mail server has blocked the message due to anti-spam filtering rules:

gmail-smtp-in.l.google.com said: 550-5.7.1
Our system has detected that this message is likely suspicious due to the very low reputation of the sending domain.
To best protect our users from spam, the message has been blocked.
Please visit https://support.google.com/mail/answer/188131 for more information.

Solution: check the reputation of the domain, determine if one of your email addresses has been recently and involuntarily exploited for malicious purposes, for example.

Domain Not Found (or DNS Error)

Le nom de domaine du destinataire n'a pas pu être résolu ou n'existe pas.

Solution: check the spelling of the recipient's domain and correct it if necessary; ensure that the domain name and DNS are valid and active.

Mailbox Full

La boîte de réception du destinataire est pleine, empêchant la réception de nouveaux messages.

Solution: inform the recipient of the situation and ask them to free up space by deleting emails or archiving items.

This cannot happen with email addresses managed by Infomaniak since they have no storage size limit.

Part of their network is on our block list

If the error message (usually obtained after sending from an online tool, placed on the server where your website is hosted, for example a order confirmation from Prestashop or another online store that you manage) contains this:

host hotmail-com.olc.protection.outlook.com[104.47.30.97] said: 550 5.7.1
Unfortunately, messages from [89.123.456.789] weren't sent. Please contact your Internet service provider since part of their network is on our block list.

Solution: change the email sending method. The sending is unauthenticated and is sent from the server with a specific IP address that is apparently blocked by the recipient for some reason (Infomaniak does not intervene to request unblocking). Therefore, you need to configure the online tool to perform authenticated sendings.

Less frequent errors

Deferred - Delayed

The error message Deferred - Delayed - Warning: message still undelivered after 4 hours, Will keep trying until message is 3 days old means that the Infomaniak mail server tried to connect to your contact's mail server to send the message but was unable to do so for an undetermined reason. This error message specifies that the Infomaniak server will continue to attempt to send your message for the period specified in the error message. If, after this delay, the message has still not been delivered, you will receive a final error message informing you that your message could not be delivered and that your contact did not receive it.

Greylisting Delay

This error Greylisting Delay occurs when the recipient's mail server, like Infomaniak, uses a technique called "greylisting" that imposes a temporary delay on the first delivery attempt of a message from an unknown sender. The Mailer Daemon may possibly send an error report indicating that delivery has been delayed due to greylisting. The error may also mention banned sender. You should try resending your message a few minutes/hours later.

Malware message rejected

This error Malware message rejected occurs when the message contains an attachment, a link to a storage site like Dropbox, or dynamic content, including in the "forwarded" part of the message (in the case of a "forward" message, for example). You should try resending the message from the Web app Mail Infomaniak (online service mail.infomaniak.com) instead of a mail application, and remove any content that may cause this error.

Message Size Exceeded / File Too Large

These errors Message Size Exceeded / File Too Large occur when the size of the message (or attachments) exceeds the limit allowed by the recipient's mail server. The Mailer Daemon will return an error report indicating that delivery failed due to the message size being exceeded.

Rate Limit Exceeded

This error Rate Limit Exceeded occurs when the sender exceeds the allowed frequency or volume limit set by the recipient's mail server. Mail servers may impose these limits to prevent spam or system overload.

Sender denied: auth guards failed

Refer to this other guide if you encounter an error Sender denied: auth guards failed.

The message contains a Unicode character in a disallowed header

This error The message contains a unicode character in a disallowed header may appear if you have inserted a special character like a heart ♥ e.g. in the body of the email, the subject or especially in the full name; the risk of being rejected by providers is very high: it is best to keep the use of signs, characters and fonts as simple as possible.