WiFi or 3G?
Is this a new problem or one you've experienced before?
You say emails can take 10 minutes, but clearly that would depend on the size of the email, so do you have any idea of the size of the email that's taking 10 minutes. As you're probably aware, nearly all current networks have higher download than upload speeds - that's the Asymmetric in 'A'DSL broadband, because it was thought that most users would download more than upload so the networks were optimised for download rather than upload speed.
Anyway, get back to us and we'll see what we can do.