[Dovecot] Dovecot imap with Postfix and using Thunderbird as client

Hi, I just recently installed dovecot, and I am having the following problem: If I send an email to my account on this new machine, I can log in via SSH and use the unix mail command, and instantly my email is visible.
If I turn on Thunderbird, it will show my new message. If Thunderbird was already on and had already checked the mailbox, even if I click on get new mail for that specific mailbox, the new mail does not show up until I restart thunderbird. Is there something that I have set wrong in the config files that is preventing the IMAP part of dovecot from refreshing the messages quickly for me to see? I dont see anything in the log files at all except for it showing me logging in. Thanks, Ben