[Mailman-Users] Mass Mail

Mark Sapiro mark at msapiro.net
Sun Apr 28 23:46:17 CEST 2013

On 4/28/2013 1:44 PM, Javad Hoseini-Nopendar wrote:
> Hi there I have a few questions about sending very large masses of
> email messages. I should remind that I don't want to do that for
> spamming purpose, but only because a friend is asking me about that
> over and over:Assume a mailing list with 200,000 members. For
> simplification purpose, Suppose all the members are from Gmail
> accounts. Now I send an email to this mailing list and the size of
> email is 1KB. I have 3 questions now: 1- This email will consume 1Kb
> of my website's monthly bandwidth or 200,000KB (200GB)? I mean my
> website's server sends the emails one by one or for example delivers
> all of them to google and google takes over the rest of work?

It depends.  If you have Mailman's VERP or personalization enabled,
Mailman will send each message to the local outgoing MTA as a 1K message
with 1 recipient; 200,000 messages all together. These in turn will be
relayed to Google's mail exchange server by the outgoing MTA in the same

If not and you have default settings, Mailman will send 'chunks'
consisting of 1 message with 500 recipients; 400 messages all together
with 500 recipients each to the local outgoing MTA. This is controlled
by the mm_cfg.py setting SMTP_MAX_RCPTS however this cannot be
arbitrarily increased. In fact, the default 500 is too big as section of RFC 5321 allows MTAs to refuse to accept more than 100
recipients in one transaction. How the outgoing MTA relays these
messages to Google's MX is up to the MTA.

> 2- If that email consumes 200GB of my monthly bandwidth, while my
> monthly bandwidth limit is only 8GB, sending that one email will
> explode and break down my whole website or it will just give me an
> error that this number is higher than allowed bandwidth?

This is a question for your hosting provider. We can't answer it.

> 3- Assume all the members have been subscribed by the list owner, not
> by their own, but at the footer of all the emails it is explained to
> them how they can unsubscribe from the list. If I send an email to
> 200,000 Gmail recepients at a time, Gmail won't send my website or my
> IP to the black list of Spammers?

This is a question for Google. We can't answer it except to say that
adding a person to a list without confirmation and relying on an
unsubscribe footer is not good practice. Good practice is to require
confirmation from every user before adding them to any list.

Mark Sapiro <mark at msapiro.net>        The highway is for gamblers,
San Francisco Bay Area, California    better use your sense - B. Dylan

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