Junk E-mail
Some of our firm's users were getting 200 or more spams per day.  They were begging for a stop to this, but did not want any real email blocked.  If you run a mail server, you can subscribe to "Block Lists".  Before doing this, research each one thoroughly.  We use Vamsoft's Open Relay Filter to do this.  This is for the IT Professional.  You must have physical control of the public MX records.  Great newsgroup support http://www.vamsoft.com/. We run this at work and block at least 3300 spams per day. Some nice ORF utilities: http://www.saganslab.com/ (I have not tried these).

Message Recall
http://office.microsoft.com/en-us/assistance/HA010917601033.aspx Read this thoroughly. Then forget it exists. Don't waste time trying to make this work. Ever.

Exchange Server - Logging outbound emails
From Peter Karsai (Vamsoft): "If you only want to know the sender and recipient of the outbound email, you can turn on the SMTP logging in Exchange/IIS SMTP and then use "grep" or a similar tool to get the relevant log entries. I am not sure if Sawmill supports such reports, but may also worth looking at that (http://www.sawmill.net/)."

Outlook 2003 / Exchange Server / Sharing mailbox resources http://office.microsoft.com/en-us/assistance/HA011134811033.aspx

Exchange 2003 - Eventlogs and Errors
http://www.microsoft.com/exchange/2003/events/

Exchange Server - various
http://blogs.brnets.com/michael/

PST files
See home computer / email section.  If you run Microsoft Exchange Server, you should never need PST files.  See http://www.swinc.com/resource/exch_faq_appxf.htm 08/2005 update - Outlook 2003 has increased the capabilities of PST files quite a bit.  The base format of the PST files were changed.

Windows Server and Exchange Server Error Code Look-up
http://www.microsoft.com/downloads/details.aspx?familyid=BE596899-7BB8-4208-B7FC-09E02A13696C&displaylang=en

Internet e-mail server utilities (Diag, SPF records lookup, blacklist lookup)
http://www.mxtoolbox.com/ This is run by postini.com, a email outsourcing firm.
http://www.kitterman.com/spf/validate.html
http://www.dnsstuff.com/