我觉得和与回答thank you 一样的。不用谢 You're welcome之类的。

In an email - say "You're welcome!" In person, if your colleague is a native English speaker, say "I am the wind beneath your wings" (it is a joking reference to a song called "Wind beneath my wings." - if you can, listen to it) then laugh, then say "you're welcome." If your colleague does not have a sense of humor, just say "you're welcome."

I'd say something like, "You're not so bad yourself! Thanks."