[MAILSCANNER] OT: Sendmail retries - bounce handling

Drew Marshall drew at THEMARSHALLS.CO.UK
Thu Sep 22 12:15:35 IST 2005

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On Wed, September 21, 2005 23:17, Venkata Achanta wrote:
> hello List,

> I am wondering what other people are doing in regards to Sendmail retries
> regarding the bounce messages.

I don't use Sendmail but Postfix does act fairly logically in these
> I think the standard practice (just a guesstimate, i havent referred to
> RFCs yet) is to retry every hour for 5 days.

Postfix uses a delay back off where if a message is undeliverable it is
moved from the active queue for a period of time. This period of time is
variable and is calculated using the length of time the message has been
delayed, i.e. the older the message, the longer the retry period.
> what is the ideal sendmail configuration to handle the bulk of outbound e-
> mail to valid email addresses quickly with least preference to retries ?

Have to let someone else have a go at this ;-
> i google around and found various option like having multiple queues and
> moving the bounce messages to other queues and forcing retries at other
> intervals. but i would like to see what other people on this list are
> doing ?

I have Postfix delete none delivered Mailer-Daemon messages after only a
couple of days, where as ordinary messages will be queued for the full 5
days. As Postfix automatically looks after it's queue there is no delay to
new messages joining the queue.

> Right now in my current configuration the "hard-to-reach" email addresses
> are creating a bottleneck for outbound email.
> i know i can avoid some of these completely by going the "accepting e-mail
> for the valid users" route.

I would definitely do this, se the wiki for some good information
regarding this.
> But there will always be DSNs from my internal users sending out bulk e-
> mails to non-existant users when they send out news letters or mass
> communication e-mails.(no flames please! i dont work for a spamming
> company
> but every org sends out some of these every now and then like monthly e-
> statments or something like that)
> Any pointers to ensure fast and efficient outbound email flow.

Personally, I would move my out going MTA to something else as IMHO
Sendmail does not handle mass mailings as well as other MTAs (Exim &
Postfix stand out to my mind) because it's single queue structure can
cause bottle necks.

Not much help I know but a different perspective none the less!


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