> Let me know if you need any other details.
Well, this would be a good time to post the output of "postconf -n", "postconf -Mf" (assuming sufficiently recent version of Postfix, else the master.cf pruned of comment lines) and any pertinent transport table entries. Also output from prior delivery attempts for the message in question, those may have tried IPv4. When both are enabled, the choice of which to prefer is random. If you don't have IPv6 connectivity, you really should disable IPv6 (by setting inet_protocols=ipv4). So just because the last delivery fails with IPv6, does not mean that IPv4 was never tried. -- Many thanks Viktor. Changing 'inet_protocols=all' to 'inet_protocols=ipv4' solved the problem. Best regards, James
