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10

The first MX means that the IP addresses in the MX record(s) for the domain you're actually attaching the SPF record to should be accepted as valid. The second one means that IP addresses in the MX record(s) for the domain mail.mydomain.com should be accepted as valid. If this SPF record is for the domain mail.mydomain.com, then the second one is redundant. ...


1

Say, the normal domain is example.com and example.net is the alias which should redirect. In DNS you have to specify the responsible mail server using the MX record, the MX for example.net would be mail.example.com are whatever the MX record for example.com is. Then all mails for example.net get delivered to the same mailserver as for example.com. The ...


7

RFC 5321 section 2.3.5 requires that domain names used in email be resolvable to addresses. From the relevant parts: Only resolvable, fully-qualified domain names (FQDNs) are permitted when domain names are used in SMTP. In other words, names that can be resolved to MX RRs or address (i.e., A or AAAA) RRs (as discussed in Section 5) are ...


1

In order for mail to function properly there are three DNS records that are required. A Record - Host name to IP address mapping MX Record - The MX record is bound to the A Record for the mail server Reverse Lookup - The IP address needs to be bound to the A record for reverse lookup (SPAM Prevention) As well, the PAT address at the firewall needs to be ...


4

MX records are fin but the domain has no dns record at all. Is that a possible error? What dns record the client should add? Yes, some mail servers, upon receipt of an email, check to see that the domain for the sending user, not just the sending server, has DNS records. I think it's a bit silly, and not a great check for spam, but it is what it is. ...


1

I need to move a client's website off their old host and onto their new host without changing their email server. You're in luck because the two things are so unrelated, asking how to move a website without affecting email is like asking "I'm moving to a new house down the street. How do I make sure I don't have to change my car's license plates?" ...


1

If destination mail server has empty free-space, then the email can't accept an email. Mail server have to store the email temporarily to queuing it before sending it to next destination. Proper mail server will throw 4xx when it's happened. It means, "I can't accept your mail right now. You may try again later" (RFC 2821 point 4.2.1). When getting 4xx-code ...


2

Choose a domain name for your mail server. The MX record should point to the FQDN (Fully Qualified Dommain Name) of the mail server, shuch as smtp.example.com. All domains should use this FQDN in their MX. Use a priority higher than 1 so that you can add servers with both higher and lower priority. Something like: example.com. mx 10 ...


1

An MX record for a domain can "point" to any host, so having them all "point" to the same server is fine. As for the preference, you can set it to whatever you like. If you add servers in the future you can add them with a higher or lower preference, dependent upon your needs.


2

Could it be that the sending servers can't connect to the primary MX and are delivering to the secondary MX as a result? If so, removing the secondary MX records will force the sending servers to queue the email for later retries to the primary MX


4

Based upon the error message it would appear that you need to configure reverse DNS lookups for the host. This is normally done with a PTR record. For example you might have a host mail.example.com mail.example.com IN A 192.0.2.1 and a PTR record 1.2.0.192.in-addr.arpa. IN PTR mail.example.com



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