[horde] ActiveSync client displays messages that were deleted in IMAP

Michael J Rubinsky mrubinsk at horde.org
Sat Aug 11 18:45:16 UTC 2018

Quoting Kevin <kevo at gatorgraphics.com>:

>> On Aug 11, 2018, at 1:10 PM, Michael J Rubinsky <mrubinsk at horde.org> wrote:
>> The ActiveSync protocol assumes either the use of a Trash mailbox  
>> that messages are moved to when deleted or that messages are  
>> expunged from the mailbox when deleted. This is one of those things  
>> that is the result of the fact that it wasn't originally designed  
>> to work against a "pure" IMAP server, but rather an Exchange server.
>> When using IMP, it is recommended to use a Trash folder.
>> For messages that are just marked for deletion using another client  
>> this is essentially just a change in flags. EAS does not support a  
>> deleted flag, however, so the message does not appear to be removed  
>> from the mailbox. IIRC, Z-push had some hack that sent a delete  
>> command to the client for those messages that were flagged as  
>> deleted. We choose not to do this as it's not an accurate  
>> reflection of the mailbox state and leads to inconsistencies when  
>> deleting items on the server vs deleting items on the EAS client.
> I see. Makes sense. I think I prefer Z-Push's behavior, but I  
> suppose Mail could be set up as an ActiveSync client as well instead  
> of IMAP.

Unfortunately, it cannot. It can only connect using a traditional  
exchange mapi connection.

> Is ActiveSync very resource intensive for Horde? I suppose I would  
> double the amount of ActiveSync load setting up all the computers to  
> use that instead of plain IMAP, but if it's not that much extra  
> resource usage it probably wouldn't matter. Or I could go to the  
> trouble of setting up email, calendars, and contacts individually on  
> the phones.

It doesn't really increase load all that much. If you are using a  
modern IMAP server that supports CONDSTORE/QRESYNC etc..., then  
polling the imap server is fairly inconsequential. It can bump up the  
database system's usage a bit, though.

> It's kind of odd that trying to maintain a consistent state of  
> things server side leads to inconsistency on the client side. One of  
> the many quirks of tech.

I would argue that it there is no inconsistency in this case. After  
all, the message actually does exist in the mailbox. The only  
difference is the EAS client doesn't mark that it's flagged with the  
DELETED flag - because it doesn't know about such a flag.

IMO, actually deleting the message over ActiveSync is inconsistent  
since now the mailbox on the EAS client shows that the message is  
actually NOT in the mailbox at all - you can't "show deleted" and you  
can't remove the deleted flag. In clients that allow marking message  
deleted, you still see them, or have the ability to show them, in the  
mailbox, albeit marked with a deleted flag which you have the ability  
to remove. You would have no such ability in the eas client if it is  
"deleted" from the mailbox.

Anyway, I do get what you are saying though :)

> Thanks,
> Kevin
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