Does anyone know of a company that will allow me to change my DNS
Gmx are using what is said to be a deprecated method of
validating email, i.e. they are checking the reverse DNS (PTR)
Reverse DNS does not use a PTR in the forward domain zone, it's a PTR in an IP
address zone, which is controlled by whoever issues the IP addresses, not the
domain name. I have two blocks of addresses, and have zones similar to the
following in my DNS server;
137 PTR mail.magsys.co.uk.
138 PTR ns1.magsys.co.uk.
139 PTR www.magsys.co.uk
140 PTR ns2.magsys.co.uk.
141 PTR mail2.magsys.co.uk.
but I have to send them to may ISP who actually controls the IP ranges to be
merged into their DNS records, which is a slow business. So you need a decent
business ISP that allows DNS updates.