I am having problems with a client who is getting added to blacklists. A couple of weeks ago they were finding that a lot of their outgoing mail to regular contacts was being put into Junk, it was the same week that a lot of their incoming mail from regular clients was going to their Junk.
They use Office 365 hosted exchange, I opened a support ticket with Microsoft and they came back to say a new update meant if a senders domain didn't have a particular record in the DNS (possibly reverse DNS?) then it would be sent to Junk. I said how ridiculous this was but they just kept saying it was by design and the workaround is to set Junk to be pre-appended with a period and then have it delivered to the inbox whilst keeping high confidence junk as sent to junk. That seemed to work but outgoing mail was still a problem.
I discovered that their domain was listed on a couple of blacklists, we think it may have been due to a mailshot being sent to a mailing list of several thousand people. They use Mailchimp (or similar) for mailshots and they only go to people who have signed up for them, although apparently they are poorly formatted so even people expecting them may have spammed them as they may not have looked professional. I have not seen the newsletter but the web designer told me this.
I had them removed from the blacklists so the domain was clean, week later some mails bounceback and I find that the static IP issued by BT is on the RATS Dyna list. There is a problem as reverse DNS was not set up (I contacted BT and it is now set up and not a problem on RATS) and the IP was on the worst offender list. The admin at RATS added our IP as an exclusion as he understood that it was owned by BT.
All of a sudden the domain is on some blacklists again!!
I need to work out why this is happening and how to prevent it going forward. Does anyone have any experience in this? If it wasn't something simple then it would be a paid job for any trusted members here if they were able to help, this is out of my usual remit but the web team at the company don't have any ideas so it's being left to me.
The IP is clean but the domain is currently on:
There are two main offices using this domain for email, one in the UK, one in the US. I have not set up reverse DNS in the US.