I read sm-mta as sendmail MTA (Message transfer agent). That seems to make sense based on the error message.

sendmail is a program that relays email messages around, either letting applications send email through it, or accepting email and routing it towards mailboxes.

So a couple of things:

• You've got sendmail installed! It's a horrible application so unless you've got a good reason for it to be installed, I suggest you nuke it.

  
  
  

  sudo apt-get remove sendmail
  
  

  
  
  

  If this moans about wanting to remove other applications which are dependent on the sendmail package, weigh it up. If those applications just need something to provide default-mta or mail-transport-agent, consider using postfix which provides those roles.




• If you need a local MTA (to handle email), I suggest postfix. Nice, fairly simple and very capable.

  
  
  

  sudo apt-get install postfix
  
  




• If you need sendmail (ie something has a hard dependency on it that you can't replace), then you want to look at fixing this specific error. Something like this might work:

  
  
  

  makemap hash /etc/mail/aliases.db < /etc/mail/aliases