I run dual-stack IPv6/IPv4 networks, including mail servers. On occasion I may not have IPv6 connectivity, but have IPv4 connectivity. When that happens, I find that my mail queue accumulates mail that arrives over IPv6, but cannot be sent out on an IPv6 interface.
(1) How to relay both IPv4/IPv6 outbound mail, regardless of whether it came to the mail server via IPv4 or IPv6? Is it possible to set up a relay action that works with either IPv6 or IPv4, perhaps with a preference for one or the other? I've tried using "src <IPv4-addr>|<IPv6-addr>" on my relay action, but this results in "No valid route to destination" errors (apparently due to the name resolution on the smtp+tls:// URL returning the address from the family opposite the selected src interface?). I'd like inbound mail to come in via IPv4 or IPv6 and go out with a preference for IPv6 but still work with IPv4 if IPv6 is unavailable. (2) How to set up a secondary relay to use if a destination relay is unavailable? Is it possible to define multiple relay hosts in one action, or to specify that a second relay action is to occur in the event of failure of the first using match rules? -- Jim Lippard lippard-opensm...@discord.org http://www.discord.org/ GPG Key ID: 0x99FD5CD6
