I have a number of Drupal websites running under several different domains. These websites must be able to send emails to users. Furthermore, I have a Zimbra mail server running. In Drupal I can either choose to send emails via SMTP or sendmail.
Actually, I'd rather use the SMTP option so that I utilize my mail server's DKIM setup. But I can't really make it work. I just got my mail server up and running today, so I'm not yet familiar with it.
But what is the best way to handle outgoing emails from multiple domains? Is it using Zimbras MTA or should I rather try to configure sendmail? It is of course a requirement that DKIM support must be provided so that my emails are not sorted out as spam.