This is probably more of a Mobile Email specific "Tip", but since I experienced it on the Rogue I'll post it here and leave it to the moderators to decide whether or not it is appropriate.
Out of the box, the Rogue could not access my daughter's Gmail account via Mobile Email even though POP was enabled on the account. The rep. at the Verizon store was very helpful and worked on it for about an hour to no avail. At this point the rep. was convinced that the problem was with Gmail's servers and to keep trying and if it did not work to return the phone.
That night, I created a new Gmail account, enabled POP, and connected right away, but still could not connected to my daughter's account. I changed her account from POP to IMAP and was then immediately able to get to her account. To make a long story short, some accounts work with POP, others have to use IMAP. The only difference is that the POP account contains only alpha/numeric characters (e.g.
jdoe@gmail.com) and the IMAP one has a dot (".") (e.g.
jane.doe@gmail.com)