The task is to process letters to tech support.Only work with email.
1.Receive email by IMAP or POP3
2.If this is not an answer to an existing ticket - assign a ticket number
3.We do the answer to the letter with quotation and ticket number in the subject line.With the ability to add your own headers, at least - the BCC field
4.Create a letter with the ticket number in the topic in the inbox for further response to it.
5.It is advisable to be able to fasten your scripts for processing - topics, headers and letter body
Should work under debian.Perhaps, just a library for php, python
No interfaces are needed - employees respond to any email client.
Free, not buggy, time-tested, works correctly with all encodings.