On 3/10/2020 4:55 PM, Stefan Bauer wrote:
Hi Noel,
i know this is quite old, but
smtp_fallback_relay should only get triggered on
undeliverable-events and not when remote replies with a 4xx or 5xx -
right?
That's what the docs say, which implies my off-the-cuff crappy
workaround is misguided.
http://www.postfix.org/postconf.5.html#smtp_fallback_relay
So the solution is to use a better ISP.
-- Noel Jones
Am Freitag, 31. Mai 2019 schrieb Noel Jones <njo...@megan.vbhcs.org
<mailto:njo...@megan.vbhcs.org>>:
> On 5/31/2019 1:48 AM, Stefan Bauer wrote:
>>
>> Hi,
>>
>> I'm running a pair of postfix-servers in different data-centers
(different ip networks) for outgoing-only delivery. once in a while
my providers /22 appear on public blacklists, so mails from my nodes
also gets rejected.
>>
>> For this, i have now a third backup-instance in another data
center that is not visible to my users and only fairly with dummy
mails used to keep reputation up and good. Howto re-route traffic on
demand with postfix in case, ip-networks get blocked again?
>>
>> How do others handle this?
>>
>> Thank you.
>>
>> Stefan
>
>
> Much better to send all your mail via the ISP that doesn't get
their whole space blocked, rather than a crappy workaround.
>
> For a crappy workaround, you can use smtp_reply_filter to turn
5xx rejects due to blacklists into 4xx temp failures, then use
smtp_fallback_relay to send the temp failures to your backup
server. This will send other mail to the backup server, such as
greylisted mail or mail that temp fails for unrelated reasons. Try
to make your reply filter narrow enough that it doesn't transform
rejects for non-rbl reasons, such as unknown recipient.
>
> http://www.postfix.org/postconf.5.html#smtp_reply_filter
> http://www.postfix.org/postconf.5.html#smtp_fallback_relay
>
>
>
> -- Noel Jones
>
