On Fri, 21 Oct 2016, Benoit Panizzon wrote: >We had complaints about delivery issues from hosting.com. > >After looking at the logs, it's obvious what goes wrong:
[greylisting with a 10 minute wait/backoff period] >The problem is that all attempts are made before the 10min threshold >would accept the email and whitelist the tripple. The particular service aside, this is a well known issue when greylisting is used. Combined with services not wanting to have huge queues that would otherwise be the case if they kept trying for days. I've seen many account/password recovery mechanisms send just once making it even 'worse'. Often the user will become frustrated and request it a second time (but that's not always allowed!) which has the same issue especially as your users probably have no idea they need to wait at least your wait/backoff period. And if the sender doesn't come from within the (usually very small) block that your software considers an equivalent sender it likely failure to receive is all but certain. The usual solution is to ditch greylisting, but it may be that reducing the wait/backoff period would suffice (e.g., to 3 minutes) or for this specific case exempt hosting.com from greylisting. /mark _______________________________________________ mailop mailing list [email protected] https://chilli.nosignal.org/cgi-bin/mailman/listinfo/mailop
