Exchange Online
A Microsoft email and calendaring hosted service.
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554 5.4.0 Error: too many hops when using 3rd party spam infront of O365
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Simon Wilks
5
Reputation points
Evening, quite a urgent issue.
The product is spam titan.
MX record = our.spamtitan-istance.com
Then spam titan = customername-com.mail.protection.outlook.com
We have a mail connector in Exchange online that permits all traffic from our.spamtitan-istance.com.
For the last month now select email, and when releasing mail from quarantine it fails with the error >
Remote server returned '554 5.4.0 Error: too many hops'
we analyse the mail header in mha.azurewebsites.net and its definitely Microsoft bouncing the mail back.
A good google we see the question on other forums unanswered >
https://community.spiceworks.com/topic/2291575-email-loop-from-spam-filter-to-o365
https://serverfault.com/questions/1064640/mail-loop-between-spam-filter-and-365/1140972#1140972
Have a support case open with Microsoft also, they have sugested black list, SPF record all which we have proved ok.
Anyone have any thoughts / suggestions on please?
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Yuki Sun-MSFT 41,376 Reputation points Moderator2023-08-21T03:04:56.62+00:00 Hi @Simon Wilks ,
Just wondering have you gone through the official document below and followed the best practices there?
Manage mail flow using a third-party cloud service with Exchange OnlineYou can also try reaching out to the support of the spam filter product to see if there are other customers who have similar experiences and whether there are any possible solutions to this issue.
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Yuki Sun-MSFT 41,376 Reputation points Moderator
2023-08-25T08:25:57.1533333+00:00 Hi @Simon Wilks ,
I am writing to check how things are going with this issue. Is there anything you'd like to update?
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simon wilks 1 Reputation point2023-08-25T09:05:23.75+00:00 Morning, thanks for checking in.
This is sill a issue, We have been doing much testing, We are in communication with the spam service provider “SpamTitan”
Were happy this is a Microsoft tissue as the mail is received my Microsoft then bounced back. It’s the reason for this bounce back we need to understand.
I have done a exercise last weekend where we made slow changes to deduce what the issue maybe.
Attached is my findings between two affected domains.
So far my conclusion so far is “Cannot send email to a recipient whos MX record is the same IP address as a inbound main connector”
Is there any more enhanced auditing that may be turned on so we can understand the reason for the bounce?
Regards
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simon wilks 1 Reputation point
2023-09-05T09:08:32.68+00:00 Hi - Apologies today I notice I had wrongly made the above as a answer not a comment.
Very poor from Microsoft. We have chased twice now and no response Our ticket number is ( TrackingID#2307270050003994 )
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Hasan Sayed 0 Reputation points2023-09-08T22:38:57.22+00:00 Hello Simon,
Did you get the resolution for this issue?
I'm facing the same problem
Please let me know.
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simon wilks 1 Reputation point
2023-09-11T15:05:09.5633333+00:00 HI there,
no still stuck & no answer from Microsoft support
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Simon Hester 0 Reputation points2023-10-20T13:54:34.11+00:00 @Simon Wilks
Did you ever get this solved? I'm dealing with what seems very similar issue been going on since a similar time to your first post for us it started on the 25th Aug.
Sadly MS support has been unhelpful really. All my tests suggest the issue is with a change error in O365 we never changed anything on the spam filter in use.
What made you come to this conclusion?
"So far my conclusion so far is “Cannot send email to a recipient whos MX record is the same IP address as a inbound main connector”
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simon wilks 1 Reputation point
2023-10-23T08:26:43.12+00:00 Hi no,
am 90% sure this is a Microsoft issue,
10% spam titan should know what the issue is even if its MS..
unfortunately we lost customers as a result and have now moved away from the spam titan product
No happy ending...
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Simon Hester 0 Reputation points
2023-10-23T13:39:34.8266667+00:00 I have been fighting MS since the 25th Aug.
As far as I can tell its them but trying to get them to find or admit what they have changed is proving hard.
Our customer in question has many other O35 tenants all running though the same email filter and the only difference we could find was that the 1 broken tenant had there O365 email set to EU storage.
When we test and use the IP's that are UK Geo IP's it works but if we use the DNS entry that resolves to EU Geo IP's is fails.
Our only work around right now is pointing to a single O365 IP for the relay.
I have even followed this document published by MS and still it breaks https://learn.microsoft.com/en-us/exchange/mail-flow-best-practices/manage-mail-flow-using-third-party-cloud#scenario-1---mx-record-points-to-third-party-spam-filtering
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Simon Hester 0 Reputation points
2023-12-21T13:41:04.06+00:00 Well I may have found a solution to the issue.
From some testing I have found the looping only occurs when using a wildcard certificate on the third part email filter. When i changed the certificate on the email filter to a specific cert for the domain the emails no longer loop.
Sadly no real explanation from MS about why this started to happen and why if it is the wild card cert causing this it is not documented anywhere.
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