I hope I'm not helping a spammer harvest email addresses..
Assuming ".rib" comes directly at the end of each email address:
If your string containing the email address is in C30 then
=MID(C30,FIND("SMTP:",C30)+5,FIND(".rib",C30)-FIND("SMTP:",C30)-5)
should extract one email per line as long as '.rib' always comes after
'SMTP:'