Cannot set up Plesk mail account in Outlook or Thunderbird for a domain behind Cloudflare: Unable to log in at server.

Symptoms

• Not possible to configure Outlook or Thunderbird for a domain example.com behind Cloudflare. Thunderbird shows the below error:

  Unable to log in at server. Probably wrong configuration, username or password.

• Mail settings configured automatically by auto-discover as example.com for incoming/outgoing servers.

Cause

By default, Plesk uses a domain name like example.com for incoming/outgoing mail. When a domain is behind the Cloudflare proxy it forwards only Web traffic and blocks all others including the mail traffic. As a result, an attempt to use example.com in mail client settings will return an error.

Resolution

One of the following solutions is available:

• Disable Cloudflare for the domain in the Cloudflare dashboard

• Configure the mail account manually using mail.example.com for incoming/outgoing mail:

  First, it is required to log in to the Cloudflare dashboard and configure the DNS record for mail.example.com.
  After that, apply one of the following methods:

  Plesk GUI method

  1. Log in to Plesk.

  2. Install the Panel.ini Editor from the Extensions menu in Plesk.

  3. Open Panel.ini Editor at Extensions > My Extensions.

  4. In Panel.ini Editor, switch to the Editor tab and add the following configuration at the end of the file:

     [mail]
     clientConfig.incomingServer="mail.<domain>"
     clientConfig.outgoingServer="mail.<domain>"

  5. Apply the changes.

  SSH method

  1. Connect to the server via SSH.

  2. Open the panel.ini file using a text editor, for example vi:

     # vi /usr/local/psa/admin/conf/panel.ini

  3. Edit the [mail] section as follows and save the changes:

     [mail]
     clientConfig.incomingServer="mail.<domain>"
     clientConfig.outgoingServer="mail.<domain>"