Hi. I would like to keep this topic alive as we drifted off to some subsidary things last time... I'll start over again because I saw this strange thing again and I think that courier has a bug here.
This is what I saw:
The recipient domain "ak-online.be" has two MX records, both have IPv4 and
IPv6 connectivity (and A- as well as AAAA-records in DNS).
Then courier opens a connection to the primary MX via IPv4. The first attempt,
in this case, is blocked via greylisting by the recipient.
The second attempt (and all further ones) is done only via IPv6.
So this is what courier really does:
1. connection via IPv4 to the primary MX
2. connection via IPv6 to the secondary MX
3. connection via IPv6 to the primary MX
4. connection via IPv6 to the secondary MX
5. like 3.
6. like 4.
[...]
In your last reply, you stated that Courier does not make a preference on IPv4
or IPv6. This may be right, but that means that when a IPv6 ressource record
is found first, courier only uses IPv6. What I miss is a fallback to the other
stack if the connections fails for any reason.
When there are two MX hosts which have 2 addresses assocaiated each (one for
v4 and one for v6), there are effectively 4 possible destination addresses
that should be tried. In fact, courier does not do any second try on any IPv4
address.
This problem comes up when a connection via IPv6 should be possible but
something is broken. This could happen, but that's what fallbacks and backup
MXes are for. I just think Courier should try all possible addresses.
Bernd
--
<Beeth> Girls are like internet domain names, the ones I like are
already taken.
<honx> well, you can stil get one from a strange country :-P
signature.asc
Description: This is a digitally signed message part.
------------------------------------------------------------------------------ What You Don't Know About Data Connectivity CAN Hurt You This paper provides an overview of data connectivity, details its effect on application quality, and explores various alternative solutions. http://p.sf.net/sfu/progress-d2d
_______________________________________________ courier-users mailing list [email protected] Unsubscribe: https://lists.sourceforge.net/lists/listinfo/courier-users
