Depends on all sorts of things. You can really only ask "what's the largest message I can sent to such-and-such a person using such-and-such a route". And even then it might depend on the day of the week.
Anything under 2Mbyte I expect to work. Anything over 20Mbyte I expect not to work and find some other way of shipping it. Anything in between I might try it to see if it works or not, and I usually wouldn't put money on it either way.