Lol
Wow! Very cool (but frustrating) to see others with the EXACT problem that i've been having!
No, i cannot get mail or internet access either with my Docomo cell connection. I've been forced to getting my mail at home with my wireless or occasionally getting lucky with unsecured wi-fi places in the city. LOL - Not a very good solution when i'm trying to email my girlfriend to tell her why i'm 30 minutes late while on the train.
I'll check out the mopera tip and see how it works for me! Thanks for the advice! I'll have to promise myself to NEVER do anything except mail with that connection, or face the wrath of a giant bill at the end of the month.
As for the instant mail notification, here is what i did. First, you have to completely give up any dreams of keeping your docomo.ne.jp mail address. Next, Yahoo mail is
supposed to PUSH mail automatically, but it was not working well for me, and after a little research i discovered that many, many others have been having this same problem.
So what i did, was setup my gmail account to auto forward all of my mail (and then mark it as "read") to my web2mail address (sign up here for free here:
www.web2mail.com) which
DOES PUSH very, very well to my iphone. (Almost instantly!)
Next, I made my iphone use this new web2mail address as my "Default Account". I told my friends to use my new gmail mail as my phone email and when they send me mail there, it auto-forwards to my web2mail, which in turn immediately pushes it to my iphone. I know, i know, you are thinking "What a pain in the butt." and "doesn't that take long?" But no, it was easy and it was really almost instantaneous. I tested it for hours to see if it was going to work okay for me and i'm now satisfied that it's my best solution. (Until the gmail people start a PUSH service.)
However, whenever i REPLY to people, i always have to change my FROM to my gmail account. So maybe it would be better to simply use web2mail as your main phone mail address and forget about gmail completely. (Note that web2mail does offer a "premium service" for about $5 a month to allow you to use other mail accounts as an automatic FROM, but i'm holding out for gmail to start PUSHing for free.

)
I'll give the mopera a try and see if that allows me to start getting my mail with my cell signal.
Hope this information was useful!
Cheerz