Why is the message body not displayed in iPhone's mail app? The normal mail app correctly shows a list of mails in my mailbox including a preview of the message body. When I tap any of them, the mail opens and correctly shows the mail header (sender, subject, date etc.) but the message body is blank.

When I look at the same mailbox using Gmail webpage, I see the identical mails with message body intact so I know that it's not a problem with the mails or the mailbox itself.

I'm using not-broken iOS 4.1 on an originally Apple-unlocked iPhone 4.
I'm using Google's official setup for Google Apps on iPhone.
I've tried purging the mail/contacts/calendar settings and following Google's setup from scratch. The problem is still there.

How can I fix it so the message body is displayed?

Response to answer:
- This used to work flawlessly, but appeared recently, without any obvious change by me.
- It might have been broken by the 4.0.2-->4.1 upgrade?
- The problem appears on wifi and on GPRS/3G, in any location, and isn't related to download delays (keeping a "blank" message open for a minute doesn't make it appear).
- It also isn't fixed by rebooting the phone.

Follow-up:
This is very weird. It seems to break every few months but only lasts a few days, then magically starts working again. Before, during, and after these incidents, I just use my phone normally and don't mess with any network settings or phone settings. I honestly have no clue what's going on.
Has this setup ever worked?

Have you tried just using plain vanilla IMAP?

Is this possibly due to poor connectivity—maybe you have a weak network connection and it's just blank until the entire message downloads?