IT IS!

Since a few days ago we have had reports from customers not receiving emails sent from our domain. Today I made a test sending emails to different email services (hotmail, google, yahoo, etc.). It took from one hour and a half to two hours for emails to be received. This problem is not with one machine and it is the same whether the email is sent from outlook or from the web interface.

I reported the problem this afternoon and now mailer-daemon sent the following error:

[Status: Error, Address: <xxxxxxxxxx@varian.com>, ResponseCode 451, 4.7.550 Access denied, please try again later. For more information please go to http://go.microsoft.com/fwlink/?LinkId=526653. (AS22)]

4.7.500-699

Access denied, please try again later

Suspicious activity has been detected on the IP in question, and it has been temporarily restricted while it is being further evaluated.

If this activity is valid, this restriction will be lifted shortly

A few years ago I got the same problem with another email provider, some of the IP´s the service used were blacklisted so it was very difficult for the email to get trough until they were delisted.