Thank you so much for the quick reply. It seems that the requirements of gmail and most other smtp servers require an authentication process that was not part of the phpbb2 code...BetterSMTP is the mod that was written to allow phpbb2 the ability to connect to smtp's with advanced security...and, yes, the internal email functions of my phpbb2 board work just fine.
The rub is that this mod allowed me to access smtp.gmail.com for internal mail but, for some reason, the digest mod still errors out as noted before. That said, my newbie guess is that the digest mod does some sort of php call to the "original" phpbb2 SMTP script. I would have guessed that your mod and the BetterSMTP Mod would have crossed paths previously due to the popularity of that fix for those of us stuck with having to utilize external SMTP's.
Well, if you or anyone can take a look at the BetterSMTP Mod (http://www.phpbb.com/community/viewtopic.php?t=345265
) and describe back how to adjust any code in your Mod or vice versa to get this to work, it would be much appreciated!
It also looks like this SMTP fix that the BetterSMTP Mod addressed was integrated into phpbb3 but I'm guessing that it will be a while for great mods like yours to be integrated into the new version of phpbb.