Why does my mail disappear on both iPad and iPhone4... only sometimes. It's not in the trash so where does it go and why?

Question

Why do I lose mail from my iPhone4 and recently from my iPad2?  It happens infrequently, but when it does the messages completely disappear from my device(s); the messages are not in my trash. 

Answer 1

OK, so I decided that maybe if I "sync" my iPod instead of just copying stuff to it at will, that maybe it would fix the problem.  I did a "restore", wiping out the contents.  I set up a "playlist", and put everything that I wanted on the iPod into the "playlist".   Then I "synced" the "playlist" onto the iPod.  Every song and album now had the proper album art.  I could live with this.   Then I added another album to the "playlist", and "synced".  The new album was now on the iPod with the correct artwork.  The albums that were already on the iPod now either had their appropriate artwork, no artwork, or the artwork from the other albums that were already on the iPod, with no rhyme or reason as to which was which.  AARGH.   I wiped it out and re-added the now-explanded "playlist" and "synced" again, and every album had the right cover.   I guess the only thing to do is completely replace the contents of the iPod any time I want to add or change anything, or forget about artwork.