Linux Configure Sendmail as SMTP Mail Client ( submission MTA )

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I‘ve central e-mail server. Other servers does not need to operate as a mail server. How do I configure Sendmail as submission-only e-mail server (mail client) under CentOS / Fedora / RHEL / Debian Linux / UNIX like operating systems?

Sendmail or any MTA can work in two different modes. It can accept incoming SMTP e-mail requests and send mail from the local machine / workstation or server (cluster node). This is called outbound MTA and it always runes in a queue-only mode.

Step # 1: Disable Sendmail Daemon In a Listing Mode

Edit the file /etc/sysconfig/sendmail using the text editor such as vi, enter:
# vi /etc/sysconfig/sendmail
Modify the line:


Save and close the file. Setting DAEMON=no tells Sendmail to execute only the queue runner on this machine, and never to receive SMTP mail requests on port # 25.

Step #2: Configure Mail Submission

You need to tell sedmail about a central MTA which will accept mail on port # 25 for all your domains. For e.g. act as a central MTA. Edit /etc/mail/, enter:
# vi /etc/mail/
Find the line beginning with D{MTAHost}, and update it to read as follows:


Save and close the file. is the hostname of the server to which this machine should forward its all outgoing mail. Please note that must be configured to accept mail from your other workstations or server. Once done reload sendmail.

Posted by: Vivek Gite

The author is the creator of nixCraft and a seasoned sysadmin and a trainer for the Linux operating system/Unix shell scripting. He has worked with global clients and in various industries, including IT, education, defense and space research, and the nonprofit sector. Follow him on Twitter, Facebook, Google+.

16 comment

  1. I’m using my own sendmail server like as MTA(outbound) and if I need to relay mails of host what settings need to be adjusted in host ?

  2. Hi vivek,
    will this work for
    -SMTP authenticated mail servers as well
    -SSL/TLS supported mail servers
    -Mail servers not running on port 25.

    The server in question is google hosted mail server. Can you give any links which details how to point local sendmail to our gmail server to send outbound mails.

  3. Hello, and thank you for this interesting article.
    I wanted to follow those indications, but unfortunately, when running on Fedora 19 release, the sendmail version has been updated to 8.14.7-1, and the content of the /etc/sysconfig/sendmail has been modified.
    the option : DAEMON = no doesn’t seem to exist anymore, and I would like to keep this parameter with the current version of sendmail.
    Do you know where i could have the same option in 8.14.7-1 ?
    I can’t find anything on the internet referring to this :/

  4. When I send mail from my smtp server to a user, the original message received by that user
    contains my ip address logged in the header. How do I change or remove that ip address?
    Please reply ASAP.

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