You have most likely finished it all by now. I just had a suggestion for
the ".rib" and ".RIB" issue. By using an IF and ISERR statements, you
should be able to capture anyone of the two in the same formula.

=IF(ISERR(MID(L13,FIND("SMTP:",L13)+0,FIND(".rib",L13)-FIND("SMTP:",L13)
--4))=TRUE,MID(L13,FIND("SMTP:",L13)+0,FIND(".RIB",L13)-FIND("SMTP:",L13
)--4),MID(L13,FIND("SMTP:",L13)+0,FIND(".rib",L13)-FIND("SMTP:",L13)--4)
)

SMTP:john.smith@...
SMTP:john.smith@...