[CentOS] advice needed about "554 Too many recipients"

Rudi Ahlers rudiahlers at gmail.com
Mon Aug 17 07:05:34 UTC 2009

On Mon, Aug 17, 2009 at 2:03 AM, Bart Schaefer<barton.schaefer at gmail.com> wrote:
> On Sun, Aug 16, 2009 at 3:50 PM, Rudi Ahlers<rudiahlers at gmail.com> wrote:
>> A client of ours just requested to increase the max_recipients in Exim
>> to 300, since he keeps getting "554 Too many recipients" error when
>> sending a marketing email from MS Outlook.
>> I would like to know, what are the implications of increasing the
>> default 100 to 300? If 300 email recipients were added to the "To:"
>> field, does it establish 300 connections to the SMTP server, or not?
> Locally between Outlook and Exim, no, this won't establish more than
> one connection to the SMTP server.  If Exim is acting as a smart
> relay, it'll get one copy of the message with the whole list of
> addresses in one transaction.
> On the "other side" between Exim and the eventual recipients of this
> mail, the likelihood is that Exim will make one or two connections per
> destination domain.  If all 200+ recipients are at the same domain
> (say, all yahoo.com addresses) then Exim may run into problems, but
> it's not very likely.
> However, if that list grows very much larger, both you and your client
> are going to be a lot happier if the client stops attempting to send
> out his own marketing mail with Outlook and instead engages a
> reputable email service provider.  Assuming, that is, that he has
> appropriately confirmed permission to send email to all those people.
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Thanx Bart, this explains a lot :)

So, as I have feared, I could run into problems with being blacklisted
by other mail server then. The client does has legit email addresses,
and wants to use Outlook (not everyone can use Linux ;)) since it
embeds the images, instead of linking to it on the internet.

The exim server in question is a hosting mail server, i.e. it's a mail
server, and not a smart relay.

I'll see if I can convince the client to use an alternative method of
doing this.
Kind Regards
Rudi Ahlers
CEO, SoftDux Hosting
Web: http://www.SoftDux.com
Office: 087 805 9573
Cell: 082 554 7532

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