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Can I use an additional port other than port 25 for SMTP connections? I was told I should open up one more ports for SMTP because most ISPs block port 25 now.

  • Parallels Plesk Panel for Linux/Unix
  • Parallels Plesk Panel 10.1 for Windows


Can I use an additional port other than port 25 for SMTP connections? I was told I should open up one more ports for SMTP because most ISPs block port 25 now.


(Parallels Plesk Panel 9.5.x - 11.x)

By default, Plesk 11 accepts mail submission on TCP port 587.

Open Tools & Settings > Mail Server Settings (in the Mail group). Select the Enable message submission checkbox

We recommend you to use Plesk web-interface to configure Postfix Submission port. If you will configure smtp submission port directly in MTA, the setting can be overwritten by Plesk.

Follow the instructions below to configure an additional SMTP port for your MTA:

QMail (Parallels Plesk Panel 8.x, 9.x)

Choose any unused port and add it to the /etc/services file. For example:

  smtp_alt 25025/tcp # new SMTP port  

If you have 'xinetd' as a super-server, make a copy of /etc/xinetd.d/smtp_psa to /etc/xinetd.d/smtp_psa_alt and correct the service line within the new file:

service smtp_alt

Restart xinetd /etc/init.d/xinetd restart and the SMTP connections will be accepted on both the standard and 25025 ports. You may also need to reconfigure Horde IMP (webmail) settings so they also use the alternative SMTP port. This can be done in /etc/psa-horde/imp/servers.php file under the smtpport parameter for both IMAP and POP3 servers.

If you have a 'netd' super-server (Debian or FreeBSD), modify inetd.conf to enable an additional SMTP port:

grep '^smtp ' /etc/inetd.conf | sed 's/^smtp/smtp_alt/' >> /etc/inetd.conf

and restart inetd.

NOTE: If you wish to disable the default (25) port completely and continue using only an alternate one, please do not block the 25 port at the firewall and do not remove the smtp_psa service from the xinetd/inetd but set the default SMTP service to be listened only on by adding bind = to /etc/xinetd.d/smtp_psa. Otherwise, the SMTP service status will be displayed incorrectly in Plesk CP. Plesk determines SMTP service status by checking the 25th port and the port number is hardcoded there.

Postfix (Parallels Plesk Panel 9.x, 10.x, ...)

Add the following line to the Postfix configuration file /etc/postfix/

<IP_Address>:<port> inet n - n - - smtpd

where <IP_Address> is the IP address of your server and <port> is the additional port for the SMTP connection.

If Postfix is configured to use Postfix Before-Queue Content Filter extend the line with the proxy filter settings:

<IP_Address>:<port> inet n - - - - smtpd -o smtpd_proxy_filter=

Reload the mail service with mailmng after the reconfiguration:

# /usr/local/psa/admin/sbin/mailmng --reload-service
Reloading postfix: [  OK  ]

Search words:

Must issue a STARTTLS command first

port 25 is blocked

smtp server issue

not working 587 port


port 587


Message submission

56797cefb1efc9130f7c48a7d1db0f0c 49af2da0f2dd4c81e962790bbbd0c2b4 5d735c0e028ee5b991e4fb80d34fb87f ec6d78150f157dcf9ef9cca1654d860c 5fc602d72ea565f353b9320e2ef62a1b 04f1b0f9f311a40f2f06e7821a7faf9a

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