My system creates a ticket in OTRS 5 with data about two parties that should communicate with one another, but only so that all communication is logged in OTRS when any one of them replies.
Unless they explicitly communicate each other's e-mail addresses and use those ones to talk directly, that is, of course.
Is there an extension or other software to do this?
Using a mail server instead of OTRS requires both the mail server and OTRS to have access to both parties' identities so the server can link both, so this is probably less ideal.
Looks like an easier solution is to hack the mail server and use something like procmail and use it as a MITM rather than fiddle with OTRS extensions which may cause problems when upgrading OTRS.
The idea is to reversible-encode the participants' e-mail addresses and use those as virtual addresses (and maybe add some signature or something to prevent an open-relay disaster).
E.g. [email protected] becomes [email protected].
E-mail headers are rewritten (From, Reply-To, To, Cc, Bcc) to enable the MITM server.
An OTRS ticket is created first to get its ticket ID and embed it into the subject so that we can send out a copy to OTRS whenever mails are exchanged.