My fight against Microsoft Outlook hotmail etc email blocking

[exxos]

@stephen_usher So what exactly do you think I should have for CNAME for exxoshost and exxosforum ?

I assume exxoshost CNAME should be exxosforum ? And vice versa maybe ?

[stephen_usher]

The A record should be for the mail domain host with the MX record pointing to it. exxosforum should be a CNAME so that web browsers/servers etc. can find it and use it. A CNAME is basically an alias and normal users won't see any difference than an A record. It would mean, however, that if someone does a reverse look up of the numeric IP address they will always find that specific A record. If you have multiple A records pointing to the same numeric address the reverse look up will find a random one of those names, whatever was in the DNS server's database as the first entry.

[stween]

Wading into a thread very late, but: is exxoshost.co.uk still the domain you're using for email? The most recent mail I have from your store (which is not super recent!) is from exxoshost.co.uk and the messages upthread suggest this is still the case. That's the domain that mail servers are paying attention to.

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$ dig +short mx exxoshost.co.uk
10 exxoshost.co.uk.

What the IP addresses for this domain map back to in the DNS are the important parts:

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$ dig +short aaaa exxoshost.co.uk.
2a00:d880:11::243

$ dig +short -x 2a00:d880:11::243
exxosforum.co.uk.

The reverse lookup doesn't get you back to the domain you started from.

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$ dig +short a exxoshost.co.uk.
185.52.2.172

$ dig +short -x 185.52.2.172
www.exxosforum.co.uk.

Same, the reverse lookup doesn't get you the domain you started from.

Setting the PTR records for those IP addresses to "exxoshost.co.uk" will align that side of things. I don't think you're using exxosforum.co.uk for any mail?

[burn]

I have to chime in here.

The last mail I received from exxos contains the following in the header

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Received: from exxosforum.co.uk (www.exxosforum.co.uk [185.52.2.172]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits)

The sending server is exxosforum.co.uk. This has nothing to do with the sender address noreply@exxoshost

What does not match, is the MX entry for exxoshost.co.uk

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C:\Users\n.huehn>nslookup -type=mx exxosforum.co.uk 8.8.8.8
Server:  dns.google
Address:  8.8.8.8

Nicht autorisierende Antwort:
exxosforum.co.uk        MX preference = 10, mail exchanger = exxosforum.co.uk

C:\Users\n.huehn>nslookup -type=mx exxoshost.co.uk 8.8.8.8
Server:  dns.google
Address:  8.8.8.8

Nicht autorisierende Antwort:
exxoshost.co.uk MX preference = 10, mail exchanger = exxoshost.co.uk

The MX entry for exxoshost.co.uk must also be exxosforum.co.uk.
This is because the receiving server checks which server the mail is coming from. Checks the MX of the domain of the sender address to see if it matches the sending server. And it doesn't do that here.

Unfortunately, there are a lot of little things that need to be done to ensure smooth mail server operation.

[exxos]

The mail should be coming from exxosforum. But this will be only valid for store orders as the forum uses idnet mail server currently. Exxoshost accounts for the store receipts i changed for exxosforum accounts, but maybe I forgot to change the no reply address from exxoshost. But I didn't think it would matter anyway.

I find all the mx and cname stuff a bit puzzling. I've got 4 domains using the same mail server. Sometimes I send from a exxoshost email but i think I gave up with thunderbird and just used the servers IP rather than any domain names.

Maybe I can send the DNS records to one of you guys to tell me what I need to change with it all ?

[stween]

Ah ok, if exxosforum.co.uk is the domain being used for mail, then:

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$ dig +short a exxosforum.co.uk.
185.52.2.172

$ dig +short -x 185.52.2.172
www.exxosforum.co.uk.

^ change the PTR (reverse) record for 185.52.2.172 to 'exxosforum.co.uk.', i.e., not www

and:

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$ dig +short aaaa exxosforum.co.uk.
2a00:d880:11::243

$ dig +short -x 2a00:d880:11::243
exxosforum.co.uk.

^ this looks okay.

@burn is probably right also on setting the mx record for exxoshost.co.uk to "exxosforum.co.uk". Or, update the noreply address to noreply@exxosforum

If no email address you're using points to exxoshost.co.uk, doesn't originate from exxoshost.co.uk, etc, there's no need for anything to query for exxoshost.co.uk's MX record, you could just remove the MX record entirely.

[exxos]

Ok thanks I'll have a look when I get back home tomorrow.

I still have a lot of exxoshost email accounts in use, but they for my suppliers and such.. there's 2 or 3 other domains which may need tweaking also :roll:

[exxos]

^ change the PTR (reverse) record for 185.52.2.172 to 'exxosforum.co.uk.', i.e., not www

The only place www is in the CNAME, and it wants me to put something in that box. AAAA has @ not www. But apparently without www as an alises the domain www.exxoshost.co.uk would stop working.. So I don't get whats its supposed to be.

I just envision if I use CNAME as exxosforum for all my domains, that me other domains will end up screwing up and doing to exxosforum also.. my 2 other domains are nothing to do with exxoshost or exxosforum, so I just see it all screwing up if I mess with it :(

The noreply address is already exxosforum it seems. So that likely changed some months ago.

EDIT:

On, it was in the server control panel. I've just changed that.

[exxos]

The MX entry for exxoshost.co.uk must also be exxosforum.co.uk.
This is because the receiving server checks which server the mail is coming from. Checks the MX of the domain of the sender address to see if it matches the sending server. And it doesn't do that here.

I've changed all the MX records to exxosforum.

Will have to wait a a few hours see if anything breaks before doing anything else.

So should CNAME be exxosforum for all my domains then ?

[stween]

^ change the PTR (reverse) record for 185.52.2.172 to 'exxosforum.co.uk.', i.e., not www

On, it was in the server control panel. I've just changed that.

Looks fixed:

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$ dig +short -x 185.52.2.172
exxosforum.co.uk.

I've changed all the MX records to exxosforum.

Alright:

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$ dig +short mx exxoshost.co.uk
10 exxosforum.co.uk.

$ dig +short mx exxosforum.co.uk
10 exxosforum.co.uk.

So should CNAME be exxosforum for all my domains then ?

I see two CNAMEs: one from www.exxosforum.co.uk to exxosforum.co.uk, and another from www.exxoshost.co.uk to exxoshost.co.uk. Neither seem related to your mail setup, and you're already issuing an HTTP-layer redirect for web traffic that arrives at exxoshost.co.uk. Seems fine to me.