Configure Docker container to send an email

I am trying to Configure Docker container to send an email…
I have run the docker centos image & mapped 25 port with 25 port of the host machine…|
What all do i need to do to send an email ?
MTA i want to use is SENDMAIL

Also getting this error

Redirecting to /bin/systemctl start sendmail.service
Failed to get D-Bus connection: No connection to service manager.