Mails generated by contact forms or scheduled tasks are not sent. The following error messages appear in
journal: plesk sendmail: handlers_stderr: DATA REPLY:554:5.7.0 The message could not be sent. You are not allowed to use sendmail utility.#012REJECT
journal: plesk sendmail: REJECT during call 'limit-out' handler
The option Turn on limitations on outgoing email messages is enabled at Tools & Settings > Mail Server Settings.
sendmail utility is disabled.
Allow users and scripts to use Sendmail: