Sending (not getting) alerts by email



My question is about plugin which can connect to IMAP mailbox analyze new email and create events from them. Similar how Tech Support systems create tickets.
Let’ s say I have external system and I have Nagios running internally. I do not want to open firewall but I want to send email (signed with a special key for security) in a special format to a particular mailbox and let Nagios about an event this way.

Something tells me this should already exist.

Thank you