SMTP / SPF issues - blocked emails to / from SWGfL

[Meldrew]

Hi,

 

Edit: removed initial pointless request I now can see wouldn't help at all!

 

Details if anyone can help, regarding SPF records and email blocking:

 

We're in the process of moving away from SWGfL, our cease date is the end of the month. Before then, we decided to move our domain name hosting away from SWGfL which itself went just fine.

 

This all of a sudden, however left us with emails to our school not working (we use an onsite exchange 2010 server using a smarthost point to SWGfL's smarthost server). A bounce back would be generated from within SWGfL saying that the email could not be routed correctly. I assume SWGfL had deleted the DNS info and therefore couldn't route correctly anymore.

 

Therefore we decided to move away from SWGfL's smarthost system and set exchange to send directly to MX records using the destination email address domain. This worked generally, except for emails to SWGfL hosted email, but easymail appears to be unaffected strangely.

 

We're now getting the following bounce error:

 

Relaying denied. IP name lookup failed [81.168.28.62]

 

The IP address is the outgoing IP through which our exchange server is sending the SMTP traffic, and the MX record for our domains points to this IP. Doing some research (so be aware I know very little about what I'm talking about now!), it appears we need an appropriate SPF record, so we change the one which has SWGfL info to be:

 

v=spf1 a mx ip4:81.168.28.62 ~all

 

But still it doesn't seem to work. We have waited 24 hours replication time, to no avail. I think I might need to get the domain host to setup a PTR record for the IP address, which I have asked them, but I thought I'd also ask the collective wisdom of edugeek for help too.

 

Any pointers?

 

Many many many thanks in advance.

 

Meldrew

 

PS. Just looking in the exchange outgoing queue, I'm seeing quite a few emails unable to be sent, so I think its not just SWGfL blocking us - its anyone that does checks on incoming SMTP traffic in the same way... Help!

Edited November 4, 2015 by Meldrew
Slight return of sanity

[Opendium_Steve]

We're now getting the following bounce error:

 

Relaying denied. IP name lookup failed [81.168.28.62]

 

The IP address is the outgoing IP through which our exchange server is sending the SMTP traffic, and the MX record for our domains points to this IP.

 

There are no PTR (reverse DNS) records for this IP address - many (most?) mail servers reject emails from IP addresses that don't have reverse DNS records. You'll need to ask your ISP (Eclipse?) to set up a reverse DNS record for this IP.

 

Also a separate word of warning: it's advisable for the source IP address of your outgoing mail to be different to the source IP address of all your other traffic, if possible. This is because if you end up with malware on your network, your IP can end up on a spam blacklist even if your firewall blocks the malware's SMTP connections (which it should), because some email blacklists are unfortunately triggered by web requests as well as spam emails - a questionable practice if you ask me, but there we go.

[Meldrew]

Thanks, @SteveHill. It was indeed PTR records, plus SWGfL completely messing up routing for our domains. After a week, we think they might have now sorted it. Also we're now free! Switched to a BT leased line yesterday. For anyone else that does this, we found that youtube broke as SWGfL (et al) have their own youtube DNS entries, so its necessary to wipe your DNS server cache to get rid of these.

 

Meldrew