I'm looking for a terminal-based mail client (specifically IMAP) that can operate in online only mode. Most people seem to be looking for mail clients with certain synchronization capabilities, but I explicitly do not want any data stored or synchronized locally. It should operate fully online, just like a webmail client.
This includes configuration. The program should not store configuration anywhere, and these options should not be configurable from within the program itself.
Additionally, I'd need to be able to pass the IMAP server and credentials as arguments to the program (either directly or via a config file argument). Effectively, I'm looking for a webmail client, but a terminal client, rather than something browser based.
In summary, it needs to be a client that essentially does not touch the underlying filesystem at all (apart from maybe a unique temp file while it's running). For instance, if a client is capable of browsing the file system to add an attachment, I need to be able to disable this.
I realize this is a bit unusual for a full mail client, but there are webmail packages out there that can do this, so I'd think there must be some mail client that can operate this way as well.
For context, this is for deployment on a terminal server for folks to check their email. The IMAP server is running locally, so it's redundant and wasteful to cache anything.
Does such a mail client exist? I'd prefer to not have to write my own, but in looking at the various clients out there, e.g. mutt, alpine, etc. I'm not having much luck. Most terminal based clients in particular seem to pretty heavily rely on the local system for caching and other operations.