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.

Refer to this other guide if you are looking for information about errors of type "mailer daemon" or "delivery failure" after sending an email.

Always use…

• the single server name: mail.infomaniak.com (for incoming IMAP and outgoing SMTP 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)
• 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.