[imp] Update - certain emails blocking ActiveSync on iPhones

[Sebastian Arcus]

On 12/10/2021 20:54, Michael J Rubinsky wrote:
> 
> Quoting Sebastian Arcus <s.arcus at open-t.co.uk>:
> 
>> Further to my thread from a few weeks ago, this has started happening 
>> on a second iPhone at the same site. Emails on this iPhone have 
>> stopped syncing completely 4 days ago.
>>
>> This time, after the hints from Michael J Rubinsky, I've taken a 
>> closer look at the inbox of the affected account on a computer, and 
>> the email immediately after the last message which has synced 
>> successfully on the phone has the following subject line:
>>
>> <<PR:63364>><<IR>> Site Inspection Report, Marshalswick, St Albans
>>
>> There were 7 emails with this subject line - part of a thread. After 
>> moving them away from the inbox to another folder, the sync resumed 
>> instantly on the iPhone.
>>
>> Is it possible that some characters in the subject line above trip 
>> Horde, or the ActiveSync protocol somewhere? If I reconfigure the 
>> iPhone to use imap, it syncs all messages of any type, without 
>> complaints - so the issue seems to be somewhere between ActiveSync, 
>> Horde and the Mail app on the phone.
> 
> It could be anything to do with those emails, could be some memory limit 
> being hit...could be lots of things. Unfortunately debugging EAS stuff 
> is tough. I really can't look more into it without either a FULL 
> activesync log - showing all the data, or copies of the emails so I can 
> try to replicate the issue locally.  There are tons of things that can 
> trip up activesync clients and we try to catch most of them (things like 
> email headers with the wrong charset etc..).  Also, what version of PHP 
> are you using?

I have just sent you one of the emails suspected to cause the ActiveSync 
issue.

For the log - do I turn on ActiveSync logging per device - and send you 
the log for this particular iPhone - or do you want a log containing all 
the devices talking to the server?

This server has PHP 7.3.10


>>
>> Last time when this happened I also tried the Outlook app using 
>> ActiveSync / Exchange on the iPhone - and that was even worse. It 
>> refused to download any email. It kept on saying "There is no email 
>> here" when checking the inbox.
>>
>> I thought maybe the above sheds a bit more light on this issue. Please 
>> let me know if any further details are needed. I can collect some 
>> debug logs, or forward the troublesome email in full if that helps.
> 
> Indeed, a copy of the email as well as a full log would be very helpful. 
> You can forward them directly to my email address. I probably won't have 
> time to look at them for another week or so though...