OSTIF, QuarksLab, and VeraCrypt E-mails Are Being Intercepted
ostif.org
ostif.org
My recollection of how Gmail works is that posting messages to the "Sent" folder is a bit odd: in contrast to other email providers, where the SMTP server is completely separate from the IMAP / incoming server, Gmail has them connected so that if you send messages out via Google's SMTP, a copy of the message is automatically put in your "Sent" folder. (At least, this is how it worked for me, last time I checked.) This normally gets noticed because if you have your MUA set up in a sane way, where it files a copy of each sent message via IMAP into the "Sent" folder, you'll end up with duplicates. Thus, you have to suppress the normal MUA behavior when using Gmail and Google's SMTP servers.
Cf.: http://superuser.com/questions/224524/sending-mails-via-mutt...
I wonder if perhaps someone had this Gmail configuration in their MUA, and then sent messages via an alternate SMTP server. Doing this would cause the messages not to show in Gmail's "Sent" box, and if that SMTP server was badly configured or behaving, could easily cause the messages to 'disappear'.
Since many MUAs will roll from one SMTP server to another if the first one is unreachable, it's not hard to imagine this happening 'mysteriously'.
China has been known to be sloppy like this when monitoring activists but that was probably not their top level secret services who monitor hacker groups - those people are usually going to be good.
Not using gmail is probably a good start regardless though.
I have previously been 100% sure something nefarious was going on, (somebody edited this file!!) and then discovered that I was connected to the wrong server, for example.
This is only meant to help them think clearly as they investigate.