> On Apr 1, 2021, at 12:02 PM, Michael Grimm <trash...@ellael.org> wrote: > > > But it is good to know that smtp_address_preference might help me with other > ISP blocking my IPv4.
For such cases I use the transport table: master.cf: smtp unix ... smtp smtp4 unix ... smtp -o inet_protocols=ipv4 smtp6 unix ... smtp -o inet_protocols=ipv6 transport: # IPv6 slow or rejected by exampl4.net example4.net smtp4 # IPv4 slow or rejected by example6.net example6.net smtp6 This does not require any changes in global defaults. -- Viktor.