As mentioned last week or so, I've built two machines as "relay gateways"
(primary and secondary MX's) between Internet and our Imail machine, for
providing aggressive anti-spam defense beyond what Imail provides. Imail
Gate, "IMGate", is based on FreeBSD OS and the postfix mailer program.
While I was at it, I built another FreeBSD machine and put postfix and the
Listar mailing list manager on it, to host the [IMGate] mailing list:
To subscribe to my [IMGate] mailing list, click here:
mailto:[EMAIL PROTECTED]?subject=subscribe%20IMGate
What kind of anti-spam defenses does postfix/FreeBSD provide to your Imail
machine(s):
1. filtering based on banned ip address from www.Mail-Abuse.org, for
real-time black hole (RBL), dial-up users (DUL), and open-relays (RSS). In
my first week of operation, I've stopped several msgs due to open-relays,
plus DUL msg's from a spammer on Paris' CyberCable system (internet over TV
cable) and another from Australia.
2. filtering based on the sending MTA's absence from DNS (no MX or A
records) and/or no reverse lookup.
3. Full Unix or Perl-compatible Regular Expression filtering of msg headers
(but not on text body).
4. etc, etc. postfix has about the best and most complete anti-spam
features you can find.
Furthermore, the IMGate relay-gateway can, optionally, offload from Imail
all OUTGOING mail (Imail drops the mail on the gateway ip address, so Imail
has no more DNS lookups and jerky SMTP dialogs with remote servers, and no
low-speed sending and re-tries), letting Imail concentrate on POP3 and web
messaging, greatly extending the life of your current Imail machine. (
Note that the guy in here recently with 250,000 Imail accounts on one
machine took exactly this approach: having Imail forward all outgoing mail
through a local Sun machine.)
A. Because this week here in the list has seen some serious complaints
about Imail's SMTP AUTH apparently being troublesome, I want to say that
IMGate can't help with that pb directly, since (while postfix can do SMTP
AUTH) postfix has no local (to postfix machine) mail accounts and passwords
to AUTHenticate with.
B. Also, the pb's with Imail web messaging blowing up cannot be directly
resolved with IMGate, since only Imail holds the user mailboxes and runs
the Web Messaging HTTP app.
However, both of these pb's may be ameliorated by IMGate off-loading so
much nasty plumbing work from Imail, freeing Imail to perform the key tasks
of interactive user activities of POP3 and web messaging.
The IMGate list is meant for Imail sysadmins who don't know and don't have
time to learn FreeBSD and postfix well enough to put it into production in
the short term. I've done that work, now you can benefit from it. ie,
it's a very "newbie" and co-operative type of list, and will concentrate on
getting the Imail - IMGate tandem to strengthen your total Imail
capabilities and keep those Imail users happy and remaining your customers.
See ya on the list,
Len
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