PHP Mail() scripts do not work with external SMTP configured in Plesk

Symptoms

• PHP Mail() scripts do not work with configured external SMTP server. This can be verified in Tools & Settings > External SMTP Server

• The following error appears in /var/log/maillog file:

  CONFIG_TEXT: Apr 20 20:19:27 host msmtp: host=smtp.gmail.com tls=on auth=on user=user@gmail.com from=root@host.name recipients=user2@gmail.com errormsg='the server sent an empty reply' exitcode=EX_PROTOCOL

Cause

Port misconfiguration for the external SMTP server configured in Plesk.

Resolution

1. Log in to Plesk GUI

2. Go to Tools & Settings > External SMTP Server and configure a valid port according to the external SMTP server requirements

Additional information

How to configure Postfix to send emails using SendGrid