[horde] Improving ActiveSync speed on large mailboxes

[Sebastian Arcus]

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?