Thunderbird 12 should automatically detect most of the proper mail settings simply by entering your name, e-mail address, and password.
astro.umn.edu email addresses are aliases for
physics.umn.edu email accounts. For automatic setup to work if your email address ends in
astro.umn.edu you should change it to end in
Thunderbird 12 does several things which can be annoying.
First, it tries to synchronize your entire mail collection onto your local computer, which can be slow (especially from home). Second, it builds a full-text index of your messages for easier searching, but this can also be slow and is unneccessary because the mail server already provides that function.
To switch off synchronization, go to Tools → Account Settings → (account) → Synchronization & Storage for each account, and uncheck “Keep messages for this account on this computer”.
To disable the search index, go to Tools → Options → Advanced → General and switch off “Enable Global Search and Indexer”
When you want to run an extensive search of your messages, the search box has an option “Run search on server”, which will give much faster results.