Me.com smtp server not responding on wifi

Hi all,

I cannot send mail from my iOS devices over my wifi connection when using MobileMe mail in the mail app. My iPhone will send MobileMe mail via 3G,and my MacBook pro will send MobileMe mail on the same wifi network.

This is happening on 2 different wifi networks, supplied by the same ISP.

The ISP say no server or ports are being blocked as I can send from my laptop. Apple are saying it must be a problem with firmware in the devices, but my mail has been working fine on my iPhone until Sunday/Monday when it stopped working on both devices. I get an error message of the smtp server not responding.

This really has me stumped, and apple reps aren't too sure either. I am waiting till tomorrow to get a firmware downgrade to a previous version of iOS for both devices try to isolate the problem.

Devices are iPhone 3GS running iOS 4.3.1 (8g4) iPad2 running iOS 4.3.1 (8g4)

I'm posting here to see if anyone has had an issue like this, and to see if anyone can take even a shot in the dark at the problem. My head says it's a problem in the ISPs end,but then why is mail.me.com not blocked from my laptop.

Thank you for reading through this, and in advance of any help any one can offer. Hopefully banging some heads together can create a solution out of nothing!!