I use two accounts in Mail, one is my Yahoo account, and the other is Gmail. OS X 10.9.1. When I'm replying to an email from my Yahoo inbox, it gets sent from my Gmail account! At first I thought I forgot to select my Yahoo account in the "From:" field, but that would be stupid, because it should automatically be Yahoo since I'm replying an email in Yahoo inbox. When I was replying to an email from Yahoo inbox again, this time I made sure that I select my Yahoo address and Yahoo server next to it. It still got sent from my Gmail account! I clicked open the compose window again and looked at the "From" field and the server dropdown menu said "Yahoo! (Offline)". What does that mean? And I could choose my Yahoo address, but use Gmail server? Just now I intended to send a fresh email (not replying) from my Yahoo account and set the "From:" field to use my Yahoo address and Yahoo server (it didn't say "Offline"). After I clicked send, it got sent from Gmail! And when I opened the compose window it said "Yahoo! (Offline)". I tried signing in to the web version of my Yahoo mail, and the sent emails are there in the Sent folder! But I got auto-reply indicating that I sent the emails from Gmail! I'm very very confused here. What's really going on here? Is there a way to prevent Mail from automatically sending my email from Gmail if Yahoo is 'offline'? Please help. Thanks.