I'm currently brainstorming ways that a mail server can be modified to work
only with specific email clients. Ideas like user authentication and
different port numbers are good places to start, but other popular clients
can be easily configured to accomodate these changes. One possibility I'm
looking at is to have the client send a specific text string in its HELO or
EHLO command. The server would then reject any connections that didn't have
this text string.
Is this viable? If so, how hard would it be modify qmail to work this way?
I am adept at C programming and have even coded my own SMTP server in the
past. Of course, if there's already a patch out there that does this, even
better.
I'm also open to other suggestions on how to make a server work with only
specific clients. The clients will be coded in-house, so we will have
complete control over the syntax the clients and servers use.
At this point I'm not completely convinced my company needs to tie the
servers specifically to their clients, but it's being bandied about, so I
want to make sure I have a course of action ready should they decide this is
the way to go. Thanks!
---Kris Kelley
