This problem only occurs when you use the ACCC's on-campus only, non-authenticated outgoing SMTP server, smtpserv.cc.uic.edu. When you send an email message using smtpserv.cc.uic.edu, the server attempts to contact your machine via identd. Normally your machine would simply reject the connection and things go quickly. When a firewall is installed, the identd connection is blocked so the SMTP server's attempt to connect has to time out, which is where the delay comes from.
CAUTION: You might be tempted to turn the firewall off -- that is not the answer.