How to change uid in mail config

The uid setting in a mail configuration file (e.g., postfix, sendmail, or exim) specifies the user ID under which the mail server runs. Changing the uid setting can be done in different ways depending on the mail server software you're using. Here are some examples:

Postfix

In Postfix, you can change the uid setting by editing the master.cf file. You can do this by running the following command:

sudo postconf -e "mydestination_uid=your_new_uid"

Replace your_new_uid with the desired user ID. Then, restart the Postfix service to apply the changes:

sudo service postfix restart

Sendmail

In Sendmail, you can change the uid setting by editing the sendmail.cf file. You can do this by running the following command:

sudo sendmailconfig -d your_new_uid

Replace your_new_uid with the desired user ID. Then, restart the Sendmail service to apply the changes:

sudo service sendmail restart

Exim

In Exim, you can change the uid setting by editing the exim.conf file. You can do this by running the following command:

sudo exim -bP | grep daemon_user

This will show you the current daemon_user setting. To change it, run:

sudo exim -bP | grep daemon_user | sed 's/daemon_user = /daemon_user = your_new_uid/'

Replace your_new_uid with the desired user ID. Then, restart the Exim service to apply the changes:

sudo service exim restart

Other mail servers

For other mail servers, such as OpenSMTPD or Qmail, the process may be similar, but the specific commands and files may vary. Consult your mail server's documentation for more information.

Remember to restart the mail server service after changing the uid setting to ensure the changes take effect.