Cannot set up Plesk mail IMAP account in Outlook: SASL DIGEST-MD5 authentication failed: authentication failure

Symptoms

1. When trying to set up an IMAP account in Outlook or Samsung Email android app, IMAP option is not available in the "Account type" field:

   

2. One of the following errors can be found in /var/log/maillog on Plesk server:

   CONFIG_TEXT: server dovecot: imap-login: Disconnected: Inactivity during authentication (client didn't finish SASL auth, waited 179 secs): user=<>, method=DIGEST-MD5, rip=127.0.0.1, lip=127.0.0.1, TLS, session=<Uzcj+sRVW+J/AAAB></>

   CONFIG_TEXT: imap-login: Disconnected (auth failed... The issue is not reproduced in other mail clients, like Thunderbird.

   CONFIG_TEXT: SASL DIGEST-MD5 authentication failed: authentication failure

Cause

Current implementation of a DIGEST-MD5 authentication in libsasl2-2 package is incompatible with Microsoft Outlook. Additional details can be found here.

Resolution

Note: if you don't have root access to Plesk server via SSH, contact your hosting provider regarding the issue

1. Login to Plesk server over SSH

2. Create a custom configuration file and place the auth_mechanisms parameter without digest-md5:

   # vi /etc/dovecot/conf.d/00-auth_mechs.conf

   CONFIG_TEXT: auth_mechanisms = plain login cram-md5 apop

3. Restart Dovecot to apply the configuration changes:

   # service dovecot restart

Additional information

Outlook fails to send an email: SASL authentication failure