Re: Prefer IPv6 on outbound

This got me thinking so I did some serious poking around and as far as I
can tell this is a james issue. I can telnet to the gmail server over v6
just fine and I did some playing since I have my own authoritative DNS
servers. I made my servers authoritative for the
gmail-smtp-in.l.google.com zone which is the zone of all google mail
servers and if I have an A record in the DNS mail sends fine. If I only
have a AAAA record with no A at all james immediately replies with a
failure to send with the error of: There are no DNS entries for the
hostname Domain : gmail.com.  I cannot determine where to send this message.

Further if I check the james logs it says: Couldn't resolve IP address
for discovered host gmail-smtp-in.l.google.com.

Despite the fact that there is an IPv6 address james says there is no
address at all so I decided to look in the james source code and found
this
https://github.com/apache/james-project/blob/5e5b4d2a38cb82dcbca431551eb9bd4a891dd642/server/dns-service/dnsservice-dnsjava/src/main/java/org/apache/james/dnsservice/dnsjava/DNSJavaService.java#L435
which might already answer my question. It looks like james for all
intents and purposes pretends like IPv6 doesn't exist. It does a lookup
for Type.A but I can search the entire code base for Type.AAAA and never
find anything. Looks like I need to open a feature request instead of a
question unless I'm missing something.

On 5/23/20 7:35 AM, David Matthews wrote:
>> What does this have to do with my sending domain? v6 is configured on my
>> sending domain but that shouldn't matter anyway. 
> Well it could be, although in your case (scoopta.email?) I don't think it is.
>
> Another possibility is that it's a linode issue? 
>
> And as it happens I have a linode VM which is currently mailing only a single daily system report to a gmail address and I notice that gmail is checking the ipv4 SPF and that's actually not what I would have expected. 
>
> In this instance there is no james involvement, but as I said, I would have expected this to go over ipv6. I don't especially care and in the past when things definitely were going over ipv6, I've had problems with the linode ipv6 address being in a blocklist - definitely not from anything I've done of course :-)
>
> Incidentally, I found it impossible to get the ipv6 address out of this block list and I wondered at the time if whole ipv6 ranges got blacklisted due to naughtiness from a single address. At the time I solved the problem by stopping ipv6 in exim4, but that config is not in place at the moment.
>
> So maybe a linode issue?
>
> --
> David Matthews
> [email protected]
>
>
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