Alessandro Vesely wrote:
Externally administered backup MXes run into backscattering because
they don't maintain a copy of the users database.
Some don't, many do.
Hm... would you expand on that, please? I browsed a few backup MX
providers (DydDNS, ZoneEdit and Mailfail) and saw no evidence that they do.
So therefore it doesn't exist.... hmmmmmm...
Some hosting system do or did more so in the past to provide service
to smaller SMTP operators. We provide an export utility for our SMTP
operators who want to have a secondary host, MX Backup and/or a AVS MX
relay at some host. It recreates the valid email names as it would
apply to a connecting SMTP client to one of our SMTP servers during
the RCPT validation check.
An example is:
which has a specifications and format to help automate a process of
creating an export or update and emailing it to them. Our utility
uses them as an example using a email template to send the a new list
or updated names.