I’d like to apologize for the response times and outages with our mail systems over the last few days.
We first recognized the problem when a large amount of spam email was causing slow response times on our mail servers. There was such a large amount of spam messages coming in that our message scanners were becoming overwhelmed and could not keep up with the demand. What made matters worse was the email appeared legitimate on many of the preliminary checks. The messages were coming from Google’s mail servers and passed DKIM and SPF checks.
We temporarily blocked an entire class B network from Google on Friday evening. This stopped the spam attack but prevented any legitimate email originating from Google from being accepted by our mail systems. When we removed the temporary Google block on Friday night we noticed mail servers operating at normal loads. We thought the attack had stopped and everything way okay. However, we discovered on Monday, a misconfiguration in one of the mail servers caused mail to not be received and sent throughout the weekend. The misconfiguration was introduced while we were trying to find the block for the spam attack.
We now have the spam attack blocked in a way which will not compromise mail system response times. We are working with Google’s abuse prevention team to stop the attack at its source. It is continuing but we are blocking it much more efficiently now.
I know email is important to your businesses and I apologize for any problems this incident has caused.