MailEnable does not send auto-reply or notifications on Plesk Windows server

Symptoms

• MailEnable autoresponder does not send an autoreply.

• In MailEnable Management > Servers > localhost > Servers and Connectors > SMTP > Logs > Activity > SMTP-Activity-date.log following message can be found:

  CONFIG_TEXT: 127.0.0.1 AUTH xxxxx 504 Invalid Username or Password 34 18 postmaster@localhost

  ---

  CONFIG_TEXT: AUTH xxxxxx 504 User Account has been disabled by the mail administrator 62 18 postmaster@localhost

  ---

  CONFIG_TEXT: SMTP-IN XXX.MAI 984 127.0.0.1 RCPT RCPT TO: john.doe@example.com 503 This mail server requires authentication when attempting to send to a non-local e-mail address. Please check your mail client settings or contact your administrator to verify that the domain or address is defined for this server.

• After enabling debug for Plesk backend utilities (How to enable/disable debug logging for Plesk backend utilities on Windows), lines below can be found in %plesk_dir%admin\logs\plesklog_debug<date>.log:

  CONFIG_TEXT: 2019/05/23 17:36:14.024 1104 30216 Info: Create mail from='jane.doe@example.com', to='john.doe@example.net', subject='Re: Autoreply', body='Test auto-reply'
  2019/05/23 17:36:14.025 1104 30216 Info: Send mail from '"" <jane.doe@example.com>' to '"" <john.doe@example.net>'
  2019/05/23 17:36:14.038 1104 30216 Warning: SMTP Exception
  at sendMail(jane.doe@example.com, john.doe@example.net)(MessageProcessor::sendMail line 329)

Cause

Account postmaster@localhost is missed or disabled in MailEnable Management or registry.

Resolution

1. Connect to the server via RDP.

   Note: if direct RDP access to the server is not possible, contact server administrator for further assistance.

2. Go to MailEnable Management > Messaging Manager > Post Offices and check whether postmaster user exists under localhost domain. If postmaster user absent:

   2.1. Delete localhost domain from MailEnable Management.
   2.2. Disable and enable option Use the mail server installed with Plesk and the default mail account created by Plesk in Plesk > Tools & Settings > External SMTP Server.

   Note: Domain with postmaster@localhost will be recreated by Plesk automatically.

If for some reason use of postmaster@localhost is not suitable, then make sure that 127.0.0.1 is set in Host name or IP address in Plesk > Tools & Settings > External SMTP Server.

Additional Information

Auto-Reply option is not working in Plesk for Windows