I set mail-signature to a different string for each context. I then hit C to compose and choose a context to test, then in the compose window I check the value of mail-signature.
For every context the value is t, with the previous value being set to the correct value from the context. So the context is setting it, and then it's getting clobbered to t.
I don't set mail-signature anywhere else, and don't think I can set a breakpoint on a var, so **does anyone have a clue where else mail-signature could get set from**? (I'm checking in the compose window, so .msmtprc shouldn't matter since I'm not actually sending yet).