$ sudo apt-get install msmtp
Reading package lists... Done
Building dependency tree... Done
The following packages will be REMOVED
  at courier-imap mutt
The following packages will be upgraded:
  msmtp
1 upgraded, 0 newly installed, 3 to remove and 0 not upgraded.
Need to get 96.8kB of archives.
After unpacking 6323kB disk space will be freed.
Do you want to continue [Y/n]?