You have two or three choices:
-
Segmentations based on Email Address CONTAINS @gmail.com which enables Dynamic Content.
-
Use a separate Email or Email Template for @gmail and ensure that your Send Email campaign says "If List is Gmail Subscribers, then Send Gmail Email."
I like #2 better in most cases. Option 1 is great if you plan to do this for several other domains like msn, outlook, yahoo.com, etc.