If this has been asked before, please accept my apologies but is it possible to send an email which, after it has been opened self-deletes?
I ask only because this has, I think, happened to me several times recently!
This was once asked by someone on a Macintosh e-mail discussion list that I'm on, and it led to a huge argument, because the answer is quite complex, and few people actually understand how IMAP works, no matter what they tell you.
At it's most basic, IMAP works by having all of your e-mail messages reside on your e-mail host's server. They are never actually downloaded to your device. Once a message on the server is deleted (either after the designated amount of time set by the server's administrator, or by request from your e-mail client after the message is read), things are synchronized with all of your devices, and all trace of that message is erased from your devices too.
See:
The thing is, the way that different IMAP services are run (either by policy or based on how they are set up), and how different e-mail clients are set up (either by default or by the user), is all over the map. So you may have an IMAP account, where the e-mail messages are NEVER deleted from the server (this apparently is common for most business accounts, but some e-mail hosts delete e-mail messages after a certain amount of time to free up server space), or you might have an e-mail client that downloads individual e-mail messages from your IMAP account and NEVER deletes the local version, even if it is deleted on the server.
So, I guess that the answer to your question is that, yes, it's possible that your IMAP account is set up that way.
