J. Ryan Earl wrote:
> Hello,
>
> I'm having a problem with an Exim MTA that I manage. I noticed late
> last week load on the server was increasing in quantized intervals, ie
> load was going up by exactly 1 in puntuated periods. After
> investigating more, it turns out some emails were looping between exim
> processes because of a bad IPv6 AAAA record, but first I would like to
> give a bit of background and information on the server host in question
> before I ask for possible permanent workarounds:
>
> Exim is running on a RHEL4 with the default Redhat Exim RPM--I'm trying
> to not build my own version of exim:
> # rpm -q exim
> exim-4.43-1.RHEL4.5
*snip*
> Here we see the problem, the AAAA record for clsmail.com is setup
> incorrectly. The temporary workaround is to stop exim for a minute to
> let the email timeout in looping to itself, however, as soon as an
> autosearch for this user is run again the email loop starts up. Now I'm
> trying to figure out the best permanent workaround. I did some research
> and basic googling on the matter and found:
> http://www.exim.org/exim-html-4.62/doc/html/spec_html/ch13.html#id2569429
>
> disable_ipv6 appears to have been added after Exim version 4.43, so I
> can't use that.
> Instead I added the following to exim.conf:
>
> # turn off IPv6 lookups
> dns_ipv4_lookup = true
>
> However, that didn't seem to help any, the email loop resurfaces. I'm
> hoping that I won't have to build my own custom installation of Exim to
> fix this problem as this is installed on a heavily used production
> system and a new Exim installation would be a huge variable I'd like to
> avoid. Does anyone know of a permanent workaround to disable IPv6 AAAA
> lookups with the stock RHEL4 version of Exim?
>
> Thanks in advance,
>
> J. Ryan Earl
> Systems/Network Engineer
> dynaConnections Corp
> 512.306.9898
>
Sanity check. Or 'Why are you HERE'.
Exim has long-since provided the tools that you need to work around someone
elses error, but you would rather not *use* those tools by upgrading to a more
current Exim release.
You apparently haven't explored another obvious route - that of asking the
entity with the defective IPV6 DNS entry to help themselves - and the world
at-large - by fixing it.
Then why not just ask the sole correspondent with a problem for an alternate
e-mail address that works as-is so you may continue running your obsolete
installation?
Exim upgrades - save from 3.X to 4.X - are nothing like a 'huge variable'.
au contraire - they are about as transparent and backward-compatible as exists.
Bill
