[TriLUG] Sendmail questions:

[Aaron Joyner]

Please forgive the "crickets" response (or lack there-of).  What
you're essentially asking is "How do I spam people"?  I trust that
your intentions are honest, then again most sources of bulk email
(unsolicited or not) believe their intentions are honest.  :)  Asking
how to defeat the outbound spam filtering of your hosting provider
obviously raises some red flags.

As for setting up a box and using it as a relay for your email, it's
not very difficult, there are plenty of guides on doing this available
via a web search.  Rate limiting outgoing mail is also possible, as is
doing it at a specific rate per-destination.  This too is easily
discovered with a bit of Googling.  As for mail servers, I'd generally
suggest that you'll have more luck with postfix than with sendmail,
given the level of sophistication of your request.  The postfix
configuration tends to involve more flat configuration text files in
key=value format, and less macro language compiled into complicated
definition formats.

A word of warning, in advance.  Attempting to send your mail out
directly to the recipients, as you suspect, will be met with all kinds
of problems.  First off, your ISP very likely will firewall
connections from your IP, to most anywhere on the internet, destined
to port 25.  They do this to limit viruses on clueless home users'
compromised windows boxes being used as mail relays.  If your ISP
doesn't firewall your traffic, but you still use a "residential" style
connection (cable, DSL, etc) where this server will live, it's very
likely the large senders will list you as a "residential" IP address,
and not accept mail from you directly.  The common / recommended
solution is to 'smarthost' or 'relay' your mail through your ISP's
mail server.  This gives them control and responsibility over the mail
you send, and as such you're likely to see them impose limits, such as
you can't send more than X mails per hour, per account, or they shut
you down.  Hence, you're pretty much back where you started.

So, that's the rough tour of sending mail on the internet.  I hope
it's been enlightening.  If you insist on sending out repeated
mailings to a large list of users, I'd strongly urge you to setup a
mailing list, using common mailing list software such as GNU mailman.
This handles the common problem of allowing users to conveniently
unsubscribe from your mailings.  Mailman does not give you the ability
to do rate limiting, if you need to do this, you'll still need to do
it at the MTA (mail server) level.

Aaron S. Joyner



On Wed, Jan 14, 2009 at 10:27 PM, Ron Young <ronyoung at nc.rr.com> wrote:
> I have a situation where we need to send about 800 emails to a customer list
> about every quarter.  The email server is located at a commercial site,
> iPower that also hosts the web site.  They have a 500 email per hour limit
> when they lock the email account.
> The software we are using to manage the shop and send these emails is
> specific to the industry and wants to send them all in a batch without
> stopping.
> I am placing a CentOS box in the shop soon and wondered if I could get
> sendmail to accept the emails from this windoze program and send say 300
> emails to the upstream hosting site and then wait a little over an hour and
> send 300 more, etc. until the whole list for that batch is sent?
>
> Or is there an even better way to do that?
>
> One fear that I have is that if I set up a mail domain (or whatever you call
> it) that runs strictly on the shop linux box then I run the risk of getting
> on blacklists when we do these batch emailings.
>
> I have never set up or administered a sendmail server but am willing, even
> eager to learn.  I would also like it to be an outbound server only and
> never receive email so I don't have to mess with spamassassin, etc.
>
> Thanks in advance to all for the benefit of your knowledge and experience.
>
>
> Ron Young
> 919-621-9015
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