Unable to send an e-mail to Plesk mail server: connection timeout or connection refused

Refers to:

  • Plesk for Linux

Created:

2016-11-16 13:07:58 UTC

Modified:

2016-12-21 20:01:18 UTC

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Unable to send an e-mail to Plesk mail server: connection timeout or connection refused

Symptoms

One of the following errors appear while trying to send an email to Plesk mail server or from Plesk mail server to an external mail server:

connection timeout

or

connection refused

The following error can be found in /usr/local/psa/var/log/maillog :

postfix/smtp[27746]: E3B24978700: to=<example@gmail.com>, 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[10.10.10.10]:25: Connection timed out)

or

postfix/smtp[15684]: connect to external.ms[10.10.10.10]:25: Connection timed out

It is possible to send an email from outside the server to the server

When trying to connect to port 25, No route to host is returned:

    # telnet mta5.am0.yahoodns.net 25
Trying 66.196.118.37...
telnet: connect to address 66.196.118.37: No route to host
Trying 66.196.118.33...
telnet: connect to address 66.196.118.33: No route to host
Trying 66.196.118.35...
telnet: Unable to connect to remote host: No route to host

# telnet alt2.gmail-smtp-in.l.google.com 25
Trying 173.194.219.26...
telnet: connect to address 173.194.219.26: 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

25 port is shown as filtered:

# nmap -p 25 mta5.am0.yahoodns.net
Starting Nmap 6.40 ( http://nmap.org ) at 2016-10-30 21:29 CET
Nmap scan report for mta5.am0.yahoodns.net (98.138.112.34)
Host is up (0.12s latency).
Other addresses for mta5.am0.yahoodns.net (not scanned): 66.196.118.240 98.138.112.33 98.136.217.202 63.250.192.45 98.138.112.32 66.196.118.34 66.196.118.35
rDNS record for 98.138.112.34: mta-v3.mail.vip.ne1.yahoo.com
PORT STATE SERVICE
25/tcp filtered smtp

Cause

Connection issues with SMTP server.

Troubleshooting

  1. Make sure that correct IP address and port number combination are used for the SMTP server in mail client preferences.

  2. If the domain name is used instead of the mail server IP address, make sure that the domain is resolved to correct IP address:

#213912165 Error when trying to open website: "The page cannot be displayed"

  1. Make sure Plesk SMTP service is running on the server:

#213414669 How can I check that SMTP Plesk service is running OK on the server?

  1. Check the firewall settings (to get list of all ports used by Plesk see article:

#213932745 Which ports need to be opened for all Plesk services to work with a firewall?

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. Contact your ISP for assistance.

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