How to change default FROM address for mail command using sSMTP?

There are a couple of settings in ssmtp that can be manipulated to allow a change in the 'From' field of emails:

1. There is a setting within /etc/ssmtp/ssmtp.conf. By default the system selects the 'From' address but this can be altered by unchecking the FromLineOverride line:

   # Are users allowed to set their own From: address?
   # YES - Allow the user to specify their own From: address
   # NO - Use the system generated From: address
   #FromLineOverride=YES
   

   By 'unchecking' I mean remove the hash mark at the beginning of that particular line.

2. There can be settings within /etc/ssmtp/revaliases to allow a specific 'From' line from each user. The example given in revaliases is reasonably unhelpful:

   # Example: root:[email protected]:mailhub.your.domain[:port]
   # where [:port] is an optional port number that defaults to 25.
   

   But the man pages gives a much more explicit example:

   A reverse  alias  gives  the From: address placed on a user's outgoing
   messages and (optionally) the  mailhub  these  messages  will  be  sent
   through. Example:
   
    root:[email protected]:mail.isp.com
   
   Messages  root  sends  will be identified as from [email protected] and sent
   through mail.isp.com.
   

I personally do not use ssmtp instead I use msmtp where the syntax for altering the 'From' field is a lot simpler and can be contained in the file $HOME/.msmtprc:

from [email protected]

which is a lot easier...

References:

• Arch Wiki: ssmtp