Problem sending Mails

Questions and answers about how to do stuff
Post Reply
Odon Garma
Posts: 33
Joined: 08 May 2017 14:10

Problem sending Mails

Post by Odon Garma »

I'm using EFA as a smarthost for Exchange.

I found this Message at the efa admin site:
(host relay.rzone.de[81.169.145.96] said: 450 4.1.0 Don't use the Backup MX 'relay.rzone.de' while the Primary MX is available - please send your mail to xx.xxxxxx.xx [xxx.xxx.xxx.xxx] (in reply to RCPT TO command))
Can someone explain and solve thi issue

Greetz
budy
Posts: 74
Joined: 10 Sep 2017 07:33

Re: Problem sending Mails

Post by budy »

Hi,

looks like your eFa picked the backup mx of rzone.de. I just queried rzone.de's mx record and it shows something different for me:

Code: Select all

budy:~ budy$ host -t mx rzone.de
rzone.de mail is handled by 10 fwmx.rzone.de.

budy:~ budy$ host fwmx.rzone.de
fwmx.rzone.de has address 81.169.144.237
fwmx.rzone.de has address 81.169.144.234
Please check what you are getting at your end…

Cheers,
budy
User avatar
pdwalker
Posts: 1553
Joined: 18 Mar 2015 09:16

Re: Problem sending Mails

Post by pdwalker »

It seems like your exchange server is trying to send mail to the backup mx host - although as budy pointed out, the current DNS record for the domain only lists the primary.

I suggest you test your mx lookup on your exchange server and see what answer you get (use the following command: nslookup -querytype=mx rzone.de). If you get a different answer from budy's result, flush your dns cache and try again.

It would seem that at some point, the backup mx record was published and your server got that information. Maybe there primary server was down for a short while? Anyway, their policy is never to accept mail on the secondary mx host if the primary host is available.

The reason for this is, a lot of secondary mx hosts are simpler machines without all the antispam/antivirus protections that the main mail host has, so spammers often try to send mail to the backup hosts hoping to avoid the filters that would stop their garbage from being delivered.

Hope this helps.
Odon Garma
Posts: 33
Joined: 08 May 2017 14:10

Re: Problem sending Mails

Post by Odon Garma »

Thanks for your help buddies!

the primary MX is the customer own MX installation. The secondary is the rzone fallback.

It looks like, in the moment of sending the primary MX was down. so this behavior seems to be alright.

Greetz!
Post Reply