When sending lots of mails (mass mailings) via many machines, one quickly realizes that the current concept of smtp_fallback_relay is a bit problematic:
* The mass mailing gets (randomly) distributed to n machines * these n machines try sending out the mails assigned to them and will encounter mechanisms like postscreen or greylisting mechnisms * thus the initial delivery fails * the mail gets passed to the smtp_fallback_relay I wonder if a time based smtp_fallback_relay ("pass the mail to the smtp_fallback_relay after a certain period of time has expired") or using the smtp_fallback_relay after a certain number of delivery attempts (>=1) would be a worthwile addition to Postfix. Something like smtp_fallback_relay_delivery_threshold = 1 would be backwards compatible to the current behaviour, while allowing the admin to specify smtp_fallback_relay_delivery_threshold = 2 or even smtp_fallback_relay_delivery_threshold = 3 which would allow a machine to "defeat" greylisting, while still using smtp_fallback_relay for the "tough cookies". Thoughts? -- Ralf Hildebrandt Geschäftsbereich IT | Abteilung Netzwerk Charité - Universitätsmedizin Berlin Campus Benjamin Franklin Hindenburgdamm 30 | D-12203 Berlin Tel. +49 30 450 570 155 | Fax: +49 30 450 570 962 ralf.hildebra...@charite.de | http://www.charite.de