MxToolBox Blog

If your customers are receiving an error message like below, there are 2 settings that may need to be adjusted.

‘name@domain.com’ on 9/15/2006 11:11 AM
550 5.7.1 Unable to relay for name@domain.com

Configure your Exchange Server to accept mail anonymously for your domain
The directions below are for Exchange 2007, but most mail servers should have similar settings.

Please confirm [...]

We wanted to give a bit more insight into the Warning from our SMTP Diagnostic tool about ‘Reverse DNS Failing’.
When a sending server makes a connection to the recipient server, the recipient server notes the sending IP address and performs a reverse lookup. This is done by sending a DNS query which returns a Fully [...]

We wanted to give a bit more insight into the Warning from our SMTP Diagnostic tool about ‘Reverse DNS does not match SMTP Banner’.
The short answer is that the reverse IP address name is not contained in the server HELO or EHLO banner. In the example below, the string “someotherdomain.com” is not found [...]

Users of Microsoft’s free email service Hotmail are reeling this week after a huge web security breach last month. All Hotmail users are encouraged to change their passwords and be vigilant as an increase in spam activity on the site has led to web security breaches.
Individual accounts have been hacked in recent weeks, and then [...]

When a sending server makes a connection to the recipient server, the recipient server notes the sending IP address and performs a reverse lookup.  This is done by sending a DNS query which returns a Fully Qualified Domain Name ( FQDN) registered for that IP address.  If the sending SMTP address matches the domain, then [...]