One big problem there is that protocols aren't sitting still in time. As more things change, like moving SMTP to ESMTP, Rebol needed to keep up, but didn't always. R2 was closed source, which didn't help. The protocol schemes were all written in Rebol, so you could hack them, which many of us have done over time, but that was an area where docs were lacking and sorely needed, so not many people could do it effectively.

Makes sense, thanks.

I was just testing out the language a year or so ago, so it wasn't super high priority to get it to work. I didn't try very hard. I think you need to configure your email + password in the Rebol tool itself and it should work. Unfortunately a lot of the pre-packaged demo scripts call out to parts of the rebol site which no longer exist, so a little bit of bitrot.