[horde] Improving ActiveSync speed on large mailboxes

[Nels Lindquist]

Hi, Sebastian.

On 2026-07-13 9:41 AM, Sebastian Arcus wrote:
> If you could bear with me a little as this is a subject I know very 
> little about. On IMAP, one feature which really helps with very large 
> mailboxes, specially on mobile clients, is the ability to download only 
> the headers and only request the email body when the actual email is 
> opened on the devices.
> 
> I gather (if my research is correct) that EAS doesn't have a direct 
> equivalent. Instead it relies on the client requesting how much of the 
> email body it wants to receive via the TruncationSize parameter.
> 
> I also gather (if this is correct), that there is no way to configure 
> this parameter in the Gmail app on Android. Looking at the ActiveSync 
> logs, it seems Gmail requests by default 200000 (byes, I assume?). I 
> wonder if it would be feasible at all to have a configurable override in 
> Horde, in the ActiveSync section - something like 
> "override_truncationsize" - to be able to set this to zero - and thus 
> force the client to only download the headers. I think this might speed 
> up considerably loading of large mail folders - and save quite a bit of 
> storage space on client devices as well.
> 
> As it stands at the moment, I find downloading of large Inboxes over EAS 
> very slow compared to IMAP.
> 
> However, I have no idea if the above is at all feasible and workable 
> within the limits of the EAS protocol?

Do you have imap caching enabled in imp? If so, what cache driver are 
you using?

Is there a reason you need to have entire mailboxes with all historical 
mail loaded on mobile devices? It's pretty typical for the client to 
only download the last 30 days worth of messages, with remote search 
available to access older messages on demand.


-- 
Nels Lindquist
nlindq at maei.ca