Suddenly getting 100% 500 mail block responses

I have a client that sends a newsletter once every couple of weeks, and he has been doing so for close to 2 years.  He has developed a strange problem suddenly with all his subscribers.

His most recent send took a hit with every address he has, all of them returning 'Mail Block - General (MB)' bounce statuses. 

A large portion of these subscribers have received 20, 30, 40 of his newsletters over the last couple of years without issue.  He averages around 25%-28% open rate, with low bounces to these accounts historically.  The addresses make up around 25% of his total list.

The newsletter content is very similar every time, and is opted in by people through his website and by writing their details on a sign up sheet in his retail store.  He hasn't added a large number of subscribers suddenly either, his list grows slowly each month fairly consistently.  We can't see an obvious change in behavior, content or subscribers that might cause this.

I can't figure out why this time he got a 100% rejection only on There was no issue the last time, about 2 weeks ago.  Could it be an AOL  issue?  Can it be rectified?

He and his subscribers are concerned by this sudden rejection of his newsletter, however we're not sure what to tell him.

Does anyone have any advice?

Thanks in advance.

roshodgekiss roshodgekiss, 5 years ago

HI cmchris, this is very unusual - as we investigate bounces on a case-by-case basis, I've just sent you an email to request further details. As soon as we hear back from you, we'll look into what happened to your client here. Sorry for the trouble!

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cmchris, 5 years ago

Hi Ros

Thanks for the follow up.  I've just sent you an email reply :)


thechrisgillis, 4 years ago

I am seeing exactly the same issue with a client of mine. Was there a resolution?

roshodgekiss roshodgekiss, 4 years ago

Hi thechrisgillis, we investigate bounce issues on a case by case basis. In Chris' situation, AOL were refusing connections for a time, but I can't guarantee that's what's happening here.

I've just sent you an email - as soon as we get a few details from you, we'll be sure to take a look. Thanks, Chris and sorry about the hassle!

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mberger, 4 years ago

Hi roshodgekiss. It looks like we had a similar situation as @cmchris's experience with AOL happen for one of our clients on Tuesday evening. Please shoot me an email and I'll fill you in on the details.

roshodgekiss roshodgekiss, 4 years ago

HI mberger, sorry for the delay in getting back to you over the weekend. I've just sent you an email, so hopefully we can get to the bottom of this issue for you shortly.

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venncreative, 4 years ago


we're also getting this issue - is there  a common cause/fix?


roshodgekiss roshodgekiss, 4 years ago

Hi there venncreative, I see that JD on our team is working with you to determine the cause of these bounces - once we hear back from you via email, we'll certainly see what can be done.

Again, we're looking into bounce issues on a case-by-case basis - the recommendations we offer can really vary from campaign to campaign. Sorry for the hassle here!

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robinbespoke, 3 years ago

I'm having the same issue described above. Please can you send me an email so I can forward whatever details you need to investigate?

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