Do the emails go out when she hits the Send/Receive button? Does the Send/Receive window show any errors?

Have you tried moving the contents of her Outbox to a temporary folder and then just sending a test message to see if that goes out? Sometimes a message in the Outbox can have an error that will prevent any other email from being sent.

Also, is she close to or over quota on her mailbox. This can often happen if she's configured to leave messages on servers, and some email providers will disable outbound email when the account reaches its quota limit.

-SW