Mail send failure on Plesk server: "You are not allowed to use sendmail utility. REJECT"

Symptoms

• Unable to send mail messages with the following error:

  in Horde webmail:

  CONFIG_TEXT: Server is not accepting SMTP connection.

  in Roundcube webmail :

  CONFIG_TEXT: The message could not be sent. You are not allowed to use sendmail utility

• There are the following records in /var/log/maillog file:

  CONFIG_TEXT: /usr/lib64/plesk-9.0/psa-pc-remote[923]: handlers_stderr: DATA REPLY:554:5.7.0 The message could not be sent. You are not allowed to use sendmail utility. REJECT
  milter-reject: END-OF-MESSAGE from hostname.hostname[127.0.0.1]: 5.7.0 The message could not be sent. You are not allowed to use sendmail utility.; from=johndoe@example.com to=johndoe@gmail.com proto=ESMTP

• Unable to send email via Wordpress or PHP script with the following records in /var/log/maillog file:

  CONFIG_TEXT: plesk sendmail[5215]: ERROR Rejecting message: system user uid='xx' is not allowed to send mail
  plesk sendmail[5214]: handlers_stderr: DATA REPLY:554:5.7.0 Your message could not be sent. The user johndoe is not allowed to send email.
  plesk sendmail[5214]: handlers_stderr: REJECT
  plesk sendmail[5214]: REJECT during call 'limit-out' handler

• Outgoing mail limits database does not contain the subscription system user or/and subscription:

  # sqlite3 /var/lib/plesk/mail/outgoing/data.db
  sqlite> .headers on
  sqlite> select * from sysusers where name like '%johndoe%';
  sqlite>

  OR

  # sqlite3 /var/lib/plesk/mail/outgoing/data.db
  sqlite> .headers on
  
  sqlite> select * from domains where name like '%example.com%';
  id|name|subscription_id|out_limit
  200|example.com|100|500
  
  sqlite> select * from subscriptions where id=100;
  sqlite>

Cause

Inconsistency in the outgoing mail limits database.

Resolution

Note: latest 3rd-line - PPS-11082, recommended solution: plesk repair mail. Consider running it first before proceeding to further steps

1. Connect to the server via SSH.

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

2. Create a backup of the outgoing mail limits database:

   # cp -p /var/lib/plesk/mail/outgoing/data.db /var/lib/plesk/mail/outgoing/data.db.back

3. Check for any users that might be missing from outgoing mail limits database:

   # plesk db -e "select login from sys_users" | tail -n +2 | while read login; do sqlite3 /var/lib/plesk/mail/outgoing/data.db "select * from sysusers where name like '%$login%'; " | grep -q '.'; [[ $? -ne 0 ]] && echo $login; done

   The users from the output of the command above should be matched with the users in the sys_users table:

   # plesk db "select id,login,mapped_to from sys_users"
   The users who have not NULL value, but instead, an id value in the column mapped_to, are additional FTP users means. And the next step should not be applied for them.

4. Add the missing subscription or/and system user into the database:

   Note: change the "example.com" domain and "johndoe" system user in the commands below to the correct one.

   # /usr/local/psa/admin/sbin/mailmng-outgoing --add-subscription --main-domain-name=example.com

   Note: if the domain is configured as a forwarding type in Domains > example.com > Hosting Settings > Hosting Type the command below can be skipped because the systemuser does not exist.

   # /usr/local/psa/admin/sbin/mailmng-outgoing --add-sysuser --main-domain-name=example.com --sysuser=johndoe

   Note: if the issue still persists, then change the mailbox limit on the subscription from 0 to at least 1 and then re-run the commands above