Hi, On Fri, Jun 23, 2023 at 08:03:40PM +0200, Carsten Schiefner via mailop wrote: > how about elaborating a bit further on the whats and whys of your setup?
Maybe some of us could learn something from that, or maybe SendGrid would consider that to be giving an advantage to competitors. Really what I am interested in is the justification for not even retrying once when receiving the "450 4.3.2 Please retry immediately" response described by the OP. If I understand correctly, the OP had experienced missing mail from SendGrid previously, had asked why there had not been retries on a 4xx, and was told that SendGrid uses a complex rule set to decide whether to actually retry for any given 4xx or 5xx. The OP then tested that by coming up with "450 4.3.2 Please retry immediately", which also did not receive any retries at all. So this implies that if SendGrid sees a "450 4.3.2" response that it does not otherwise have a special rule for (or is it any 4xx that there is no rule for?) then discarding the mail without any retries at all is what happens by default. The idea of not retrying at all on certain specific 4xx responses doesn't sit that well with me, but I can kinda sorta see why a large sender might want to do that if they were really sure. But here seems to be the implication that it's actually quite easy to trigger that behaviour, unless by some stroke of bad luck "450 4.3.2 Please retry immediately" happened to match an existing rule. It would be useful to know if it is the case that if one uses a 4xx response that SendGrid hasn't seen before, it's going to result in no actual retries. Thanks, Andy -- https://bitfolk.com/ -- No-nonsense VPS hosting _______________________________________________ mailop mailing list mailop@mailop.org https://list.mailop.org/listinfo/mailop
