And just as an update note. The spam flagging has been really random. We also run blogs from Wpengine.com that send mail to us. Some of that email is flagged as spam and some is not. It appears to be all settings on the Office 365 side on different servers with different routes of email passage.
I've never really delved into it. But this " header too large" error is looking really consistent. Microsoft says their default max header size is 256KB, the outside servers are complaining at 32 KB. Our listserv stands out and usually notices an error first because it is actively sending email all day long to servers outside our domain. Usually a list owner will send me a notice that a confirmation email is being delayed longer than normal. Then we know something is amiss in the email world.
In the connector limits section
https://technet.microsoft.com/en-us/library/bb124345%28v=exchg.160%29.aspx?f=255&MSPPError=-2147217396 Parameter: MaxHeaderSize
From: LISTSERV Site Administrators' Forum [mailto:[log in to unmask]] On Behalf Of Eckstine, Nate
Sent: Monday, July 18, 2016 3:53 PM
To: [log in to unmask]
Subject: Re: Question regarding header size in emails
We are still getting these. Not in every message but in enough of them.
Last error: 5.6.0 552 5.6.0 Headers too large (32768 max)
I hadn't ever seen this error message until a few months ago. I believe it is all related to background changes in the Microsoft Anti Spam efforts. I can't find much on technet or google about it. I've requested our messaging admins to open a Microsoft Premier ticket on it. I'm not sure if it will get approved.
However based on Eric note here I search on 'disable this header" and see this recent Technet update. https://technet.microsoft.com/en-us/library/dn205071%28v=exchg.150%29.aspx?f=255&MSPPError=-2147217396
It's the x-spam and x-diagnostic message additions that are causing the issue I think. I'm not an exchange admin so will have to see if these can be disabled.
From: LISTSERV Site Administrators' Forum [mailto:[log in to unmask]] On Behalf Of Eric Thomas
Sent: Monday, July 18, 2016 2:54 PM
To: [log in to unmask]<mailto:[log in to unmask]>
Subject: Re: Question regarding header size in emails
I would e-mail a command to LISTSERV@xxx to see if the long header is generated on the outgoing or incoming side of Exchange (the response will be generated locally and will not have gone through the incoming side). My bet is that is happens on the incoming side and you can disable this header.
Eric
From: LISTSERV Site Administrators' Forum [mailto:[log in to unmask]] On Behalf Of Silcox, Matthew
Sent: Monday, July 18, 2016 16:42
To: [log in to unmask]<mailto:[log in to unmask]>
Subject: Re: Question regarding header size in emails
Hey Nate,
Did you ever get any leads on this? Do you know if it is, in fact, because of the massive EOP headers? I may be opening a Premiere Support Case with Microsoft if I don't find anything else on this.
Respectfully,
Matthew Silcox
Senior Systems Administrator
Client Infrastructure Group | Information Services
Kent State University
* 330.672.1290
* [log in to unmask]<mailto:[log in to unmask]>
________________________________
From: LISTSERV Site Administrators' Forum <[log in to unmask]<mailto:[log in to unmask]>> on behalf of Silcox, Matthew <[log in to unmask]<mailto:[log in to unmask]>>
Sent: Monday, July 11, 2016 5:08:02 PM
To: [log in to unmask]<mailto:[log in to unmask]>
Subject: Re: Question regarding header size in emails
We're seeing this, as well. Also in Office 365. I thought it was because we were doing a Proof of Concept for a 3rd Party spam filtering appliance, and there were some extra headers tacked on for that, but it looking more like Office 365 is the culprit.
Respectfully,
Matthew Silcox
Senior Systems Administrator
Client Infrastructure Group | Information Services
Kent State University
* 330.672.1290
* [log in to unmask]<mailto:[log in to unmask]>
________________________________
From: LISTSERV Site Administrators' Forum <[log in to unmask]<mailto:[log in to unmask]>> on behalf of Eckstine, Nate <[log in to unmask]<mailto:[log in to unmask]>>
Sent: Monday, July 11, 2016 4:59:04 PM
To: [log in to unmask]<mailto:[log in to unmask]>
Subject: Question regarding header size in emails
Hi, we are running Outlook on the desktop and Office 365 with exchange in the cloud for email delivery. Email goes to an IIS install of Listserv, then to the Microsoft Exchange cloud install, then offer to the destinations.
We have recently started getting a lot of this message in our daily monitoring reports. And the email to the recipient is not delivered.
Last error: 5.6.0 552 5.6.0 Headers too large (32768 max)
I have been testing the email headers here. https://testconnectivity.microsoft.com/
It does indeed look like the message header approached 32KB in a lot of listserv messages.
I have a dozen or so entries like this in the header analysis. I am not even sure if they are necessary. But searching the web isn't pulling up a lot of info on the X-command configuration. Technet fairly skimpy also.
X-Microsoft-Exchange-Diagnostics-untrusted
1;BD2PR09MB8883;23: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
Has anyone seen anything like this? One suggestion has been is to email the destination email admins and ask them to raise their max header size.
Another suggestion was to reinstall the connectors this system uses to place rules on the outbound emails.
Thanks nate
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