My idea to use
---
inet_protocols=ipv6
smtp_fallback_relay=smtp:[smtp.online.nl]
---
fails, since you can only specify a host, but not a transport. So
disabling IPv6 effectively disables also the ability to reach
smtp.online.nl. The alternative it to have the firewall quickly end any
IPv4 SMTP connects to anything but that particular host, however it is
no so nice.
Is there no way to have an alternative transport for fallback_relay host?
Thanks Wietse for noticing the inet_protocol*S*, it was just sloppy
writing from my part.
- Joris
Joris Dobbelsteen wrote, On 22-07-09 00:27:
Wietse Venema wrote, On 21-07-09 23:12:
Joris Dobbelsteen:
[ Charset ISO-8859-1 unsupported, converting... ]
I'm using Postfix 2.3 (with debian etch, but I'm planning to go to
postfix 2.5 with debian lenny). I'm using the postfix box solely for
relaying e-mail and doing virus/spam scanning. Mail for local domains
is relayed to a local server and everything else goes to my ISPs
server. I currently use transport_maps to manage this and that is
working fine for a couple years.
Now I want to reduce the use of my ISP mail server. For IPv4 this is
not possible: its troublesome with residential access & my ISP blocks
outgoing port 25. However I have an IPv6 ip address where mail
delivery is available.
Is there any possibility to use the "transport_maps" to indicate
multiple destinations?
No, but perhaps it is enough to set smtp_fallback_relay to the ISP.
smtp_fallback_relay = [mail.isp.example]
Wietse
I thought so. Thanks for the confirmation, suggestion and fast reply.
However that option is scaring me due to mailing loops. Postfix is
behind NAT on a residential ADSL connection, meaning it doesn't know its
Internet IP address (for certain). Besides the 'internal' hostname
doesn't necessarily reflect the outside one.
This is because "internal" is also a relay destination and I simply
cannot guarantee it's ready to receive email.
====
A better idea seems to be looking a bit deeper into master.cf and see if
I can add some entry here that does what I want. Currently it is:
---
familiedobbelsteen.nl smtp:joris2k.local
* smtp:[smtp.online.nl]
---
Of course there is already the existing "relay" entry here, so:
---
familiedobbelsteen.nl relay:joris2k.local
* smtp:[smtp.online.nl]
---
smtp unix - - - - - smtp
# When relaying mail as backup MX, disable fallback_relay to avoid MX loops
relay unix - - - - - smtp
-o fallback_relay=
-o smtp_fallback_relay=
# -o smtp_helo_timeout=5 -o smtp_connect_timeout=5
---
That should allow setting smtp_fallback_relay without interfering with
the other deliveries, right? It means I should be able to configure
smtp_fallback_relay somewhere else without any issues.
What makes me think about extending master.cf with a IPv6 direct
delivery service type, such that I add:
---
familiedobbelsteen.nl relay:joris2k.local
* direct6:
---
direct6 unix - - - - - smtp
-o inet_protocol=ipv6
-o smtp_fallback_relay=smtp:[smtp.online.nl]
---
This should work right, as I intend it? Or am I mistaken somewhere?
(Love mailing lists for organising my thoughts...)
Thanks,
- Joris
