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

Always use...

• the unique server name: mail.infomaniak.com (for IMAP reception servers and SMTP sending)
• 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 its password in the fields related to mandatory authentication
• the correct email address password which is generally different from the username used to log in to Infomaniak (if necessary, change the password of your email address) - beware of the sign $
• an existing email address that must have been actually created (or defined 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 as these two protocols do not work well together)

Mandatory to try...

• compare the recommended parameters for the software/email client used, especially if you have just modified the password on the Infomaniak side
• retrieve your emails using another network (WiFi, connection sharing 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 the configuration of your keyboard the key A may refer to the letter Z and the key Q may refer to the letter A...
• restart and try a send/receive: some applications require validating several times the window containing the configuration parameters or ask to be restarted to take into account their new parameters
• write a new message after modifying your parameters: a message in the process of being written that would be saved in the Drafts folder risks not taking into account any possible configuration changes

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: Authenticated connection 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 network traffic."
  or "the time limit has been exceeded" with an error number that follows (421, or 573 for example).
  Most ISPs (Internet Service Providers) have blocked the SMTP sending port number 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.