Sendmail MTA

 --https://share.google/aimode/TLKR3lTfULnz25CLg

Sendmail is a powerful, highly configurable Mail Transfer Agent (MTA) that routes and delivers email across Unix and Linux systems using the Simple Mail Transfer Protocol (SMTP). While traditional and flexible, many modern systems have replaced it with lighter or more secure alternatives like Postfix. [1, 2, 3, 4]

Key Files and Configuration

/etc/mail/sendmail.mc: The primary macro configuration file you edit.
/etc/mail/sendmail.cf: The raw configuration file generated from sendmail.mc via the m4 macro processor. Do not edit this file directly.
/usr/sbin/sendmail: The binary command interface used to send mail from the system or scripts. [1, 2, 3]

Managing Sendmail

Compile changes: Run m4 /etc/mail/sendmail.mc > /etc/mail/sendmail.cf after making updates.
Restart service: Run service sendmail restart or systemctl restart sendmail depending on your init system.
Test delivery: Pipe or pass messages directly via command line, such as sendmail -v user@example.com. [1, 3]

If you need specific help, please let me know:

• What operating system you are using (e.g., RHEL, CentOS, Ubuntu)
• Whether you are trying to configure relay settings, fix a bounce error, or install SSL certificates