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

[Kevin]

> 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.

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'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.

Thanks,
Kevin