Well, I don't use MyMail, and I'm not on Rogers but I think we're having the same problem. Sounds funny, eh? I'm on Fido and occasionaly over the last couple weeks Pocket Outlook will fail to check email saying that there is no coverage. Nothing I can do will fix it until I restart the phone.
I think all of this is a result of the merger between the two companies. I got a phone message from Fido just before all this started to happen saying "we are currently working on our new expanded network in your area. You may notice some intruptions due to this". So I just figured it was all merger pains.
I hope it gets back to normal soon.