I read a lot of messages but don't post too often. Pasxal
has it right most of the time. On this one, I just tweaked his
function a bit and came up with this:

=MID($A8,FIND("SMTP:",$A8),FIND(".rib",$A8)+4-FIND("SMTP:",$A8))


It seems to work, although I do see you have put in some constants
to get the job done.