Problems with ssmtp after upgrading to Ubuntu 20.04 LTS - package post-installation script subprocess returned error exit status 2
Solution 1:
I could solve the problem by checking the ssmtp.config file under /etc/ssmtp/
There is a line with the FromLineOverride=YES parameter followed by a comment. This comment seems to be the problem. When i moved the comment a line up so that only the parameter i in a line the problem is solved.