[imp] Update - certain emails blocking ActiveSync on iPhones

[Sebastian Arcus]

On 13/10/2021 00:59, Michael J Rubinsky wrote:
> 
> Quoting Sebastian Arcus <s.arcus at open-t.co.uk>:
> 
>> 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?
> 
> Use per device logging and I only need that one device's log during the 
> time it issued a sync and retrieved the results that are failing.  If 
> your version of horde has the option to enable "detailed" instead of 
> "protocol" logging for the activesync log, please enable that too (I 
> can't remember which version I introduced that in :)
> 
>>
>> 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...

I have sent you through:

1. A copy of the email which breaks the sync
2. A detailed log when the iPhone doesn't sync properly
3. A detailed log when the iPhone syncs emails properly (after removing 
the problem email message from the inbox)

Many thanks for looking into it