1. Mail OLC Training

2. Sendmail Sendmail is the Mail Transfer Agent (MTA) that’s the most common these days. Local or daemon (listen) mode Eventually, it’s what all (most) mail clients use to deliver mail that you send

3. Mail in general User gives mail to sendmail. Sendmail looks up MX records for domain. If MX records, deliver to that machine. Otherwise, assume domain is machine and lookup “A” record. If that fails, bounce. Receiving sendmail confirms that mail is for local recipient, and delivers it to mail spool. (Unless it’s a relay, but that’s special)

4. Mail at MIT Server groups – “OUTGOING”: MMC and MCS (legacy) – “MAILHUB”: GCS and CCCS – “DMZ”: FPS and PCA – “DMZA”: BISC – “DMZ-OUTGOING”: SSA – Milter boxes – PO Servers – Barracudas

5. “OUTGOING” (legacy) Gets mail from MIT users (Athena workstations via sendmail or Mac/PC via Eudora/Netscape/whatever) Goal is to accept mail as fast as possible. Some recipient checking. No brains. They just relay to the mailhubs. Load balancing via MX records. (host -t mx outgoing.mit.edu)

6. “MAILHUB” Takes mail from outgoing and delivers to “local” addresses (ie “.LOCAL”). Expands aliases Sends non-local mail to the “DMZ-OUTGOING” servers

7. “DMZ” Deliver mail from the mailhubs to non-local addresses Accept mail from other sites for MIT. (they’re the MX hosts for mit.edu) Thus any problems with mail going to/from the outside world will (in theory) not affect internal MIT mail.

8. DMZA Path for authenticated outgoing mail at MIT biscayne-one-station.mit.edu

9. PO Servers Po9 through po14 (except 13) Auth via IMAP/SSL, kpop, krb4 IMAP Where vacation happens

10. SpamAssassin www.spamassassin.org Written in Perl, customizable We use a mostly stock distribution, except we give bonus points (negative score) to mail that goes through outgoing, because outgoing is in server RBLs) Threshold is customizable (7.5 default) Spam will go into an IMAP Spamscreen folder if it exists, otherwise client must filter based on headers. Auto-purging of Spamscreen folder available.

11. Spam Screening, cont. New Barracuda boxes are MX records for mit.edu They score the mail, then pass to DMZ.

12. Vacation Will only respond if you@mit.edu is explicitly in To or Cc (or if you've added the address to the “other addresses” field) Will only respond to same sender once every {7} days. Uses message “From” http://web.mit.edu/mail/auto-responder Takes effect instantly - no DCM