The limitations in email handling in Indigo finally annoyed me enough to do something about it. This plugin allows creation of three devices, each representing an email type server. There's one for IMAP servers, one for POP servers, and one for SMTP servers. The IMAP and POP devices have triggers for email received. There's several states exposed for this, but if you want to use both subject and message body in your conditionals, trigger on the "lastMessage" state as it's the last one updated. I would use Conditionals to look for specific strings in the state fields rather than trying to do an exact match in the Trigger.
The SMTP device allows you to set up a specific email server/account to send mail "From". It has one action available, which sends an email. The advantage here is that you can define multiple SMTP devices, with different SMTP credentials and different "From" addresses. Also, variable substitution is enabled in the message subject and body.
Error handling is still pretty spotty, and you'll probably need to run it in debug mode all the time to get any useful feedback on it.
https://dl.dropboxusercontent.com/u/7563539/Better%20Email-0.0.3.indigoPlugin.zip
Feedback in this thread please.
joe