Re: Need advice on large mailing lists

[Matti Aarnio <mea@nic.funet.fi>]

...
> You may also want to keep mailing list explosions in a separate
> /var/spool/postoffice to prevent delaying your non-mailing list email.

	With present system that is not so easy, however you can
	define alternate router directories that are picked up
	when the main router directory is empty.  (ROUTERDIRS
	definition, with  "sendmail" program there is a -p -option.).

> Then there is L-Soft's LSMTP (http://www.lsoft.com), a commercial SMTP
> product especially designed for sending to large mailing lists. L-Soft claims
> 100,000 deliveries an hour running on a PC. I don't have experience with it,
> but I understand that one key difference between Zmailer/sendmail and LSMTP
> is that the latter will accept a single message with 50,000 recipients (ie no
> chunking) and work on the addresses concurrently. At bottlenecks like DNS
> resolution (which takes a long time for a signficant number of addresses on a
> large international mailing list) LSMTP can have many more concurrent DNS
> lookups outstanding. To gain that sort of concurrency with Zmailer you would
> have to break up the 50,000 recipients into 50,000 messages and run a huge
> number of routers and smtp delivery channels--but then the overhead of
> dealing with 50,000 messages would be a factor.

	I have used here an approach which you can see from  TELE-FI.cf
	sample for router.cf -file (proto/cf/ -directory).  It uses
	a list of "known toplevels", and will not do DNS lookups (to
	canonicalize names) if the last component of the domain name
	is in the list.

	That way the ROUTER does not spend time on querying the DNS,
	but the smtp channel programs can take their time -- they do
	it in parallel anyway.
 
> Alex Nishri
> University of Toronto

	/Matti Aarnio