One of the following errors appears while trying to send an email to Plesk mail server:
The following error can be found in
Jan 1 01:34:10 ip-68-178-206-153 postfix/smtp: E3B24978700: to=<firstname.lastname@example.org>, relay=none, delay=537, delays=446/0.02/91/0, dsn=4.4.1, status=deferred (connect to alt2.gmail-smtp-in.l.google.com[18.104.22.168]:25: Connection timed out)
When trying to connect to port 25,
No route to host is returned:
# telnet mta5.am0.yahoodns.net 25 Trying 22.214.171.124... telnet: connect to address 126.96.36.199: No route to host Trying 188.8.131.52... telnet: connect to address 184.108.40.206: No route to host Trying 220.127.116.11... telnet: Unable to connect to remote host: No route to host # telnet alt2.gmail-smtp-in.l.google.com 25 Trying 18.104.22.168... telnet: connect to address 22.214.171.124: No route to host Trying 2607:f8b0:4002:c03::1b... telnet: connect to address 2607:f8b0:4002:c03::1b: Network is unreachable telnet: Unable to connect to remote host: Network is unreachable
Connection issues with SMTP server.
Make sure that correct IP address and port number combination are used for the SMTP server in mail client preferences.
If the domain name is used instead of the mail server IP address, make sure that the domain is resolved to correct IP address (see article #765).
Make sure Plesk SMTP service is running on the server (see article #1387).
- Check the firewall settings (to get list of all ports used by Plesk see article #391). Ultimately, stop any firewall running on the Plesk server and try to send an e-mail again. If this does not work, then the SMTP port is blocked from somewhere else in network. Please check network and ask ISP about port 25 filtering.