[mimp] Default Identity trouble

[James Philput]

Hello,
I'm running into with Mimp that I'm hoping you guys can shed some light on.
I'm getting an error when I try to send mail from Mimp:

ERR: There was an error sending your message: Validation failed for:
jphilput at .SYNTAX-ERROR

On the Identity block it lists jphilput@(Default Identity). I don't have any
problems sending mail from Imp. I've checked the list archives, and the
previous reference to this issue was solved by switching to Composite Auth
using the HowTo in the Wiki. I tried that, and still get the same error.
I've only got one server configured in servers.php for both Mimp and Imp,
and in both files I have set the realm to match my sending domain. Does
anyone have any suggestions on how to solve this problem? Please let me know
iif you need me to post additional information.

Thanks,
James