Problem receiving email from one customer. [View all]

I use Entourage for my email and have no problems with it. It works fine for me.

Recently, I've been having trouble receiving emails from one of my customers (she uses Yahoo, I believe).

I've had to set up a Gmail account just to get her emails. This is a clunky arrangement and Gmail is exceedingly slow (it can take hours to get an email).

Where does this problem originate? My end or hers? I think it is on her end, but I don't have a clue as to how to fix it.

I'm on a iMac, 10.4.11 (I know, I know --- I should upgrade, but as Ann Landers used to say "if it ain't broke..."