The reason is that there are certain configuration settings server-side which have to be set correctly for MfE Maemo to work.
Especially the "provisioning" feature is a hindrance for many. This feature is intended to provide higher security by making sure the mobile device adheres to certain standards. The ability to completely wipe a mobile device remotely is an example of a requirement for "full" provisioning.

This is currently not possible with Maemo, because as a Linux OS, it's open and customizable, and it would require too many changes on the OS side for MfE to be able to support provisioning.
This will change in the next iteration of Maemo ("Harmattan" / Maemo 6), because it will have a dedicated DRM mode which allows the developers to implement the needed features for provisioning.
On the other hand this will make Maemo less open, which has been the topic of a heated discussion, but it will (most likely, nothing is certain at this point) satisfy the requirements for provisioning.

Vitaly, greetings. My 3 kopeiks here (absolutely IMHO):

very annoying:
1. No header is added to forwarded emails.

annoying:
1. Reminder popups for calendar entry when cancellation notification for this meeting has been received.
2. No "lookup in global address book" feature.

as a side note:
1. Inability to sync N900 if server is setup not to allow non-provisionable devices will be a showstopper for major businesses. If Nokia wants to position Maemo version of MfE for corporate customers, MfE should be programmed to support environments with "allow non-provisionable devices" feature enabled. Just because its easier for most mid to large businesses to pick solutions that do not require re-design of their security settings.

I dont think its a provisioning issue. I use non-provisional devices with no issues whatsoever on our Exchange 2007 server. My NOKIA E51 is a non-provisional device and works like a charm, but NOKIA N900 can not sync. The progress bar starts and never finishes without giving me a single error. iphone works, nokia E51 works, nokia E71 works with my server but NOT, I reapeat NOT, Nokia N900, and there are absolutely NOOOOOOOO excuses for that. Email is so essential, and NOKIA N900 fails in that

Have you tried disabling provisioning requirement for your account?

I try to find out how well the N900 works with our Exchange 2007 Server.
Windows Phones interact with Exchange server this way:

When you reply to an e-mail the phone just sends what you have written. The server receives this (short) answer text and compiles a full email including the original text, attachments etc. and sends it outside. This means:
If e.g. a hugh HTML email arrives, lets say with 1MB embedded pictures etc., the phone doesn't need to download the e-mail in full. Maybe just the first two sentences are enough for you to know what is the topic and you can forward it to an college. Even if the attachments are 30mb the e-mail is forwarded with in seconds while you are online with a slow mobile connection.

Most annoying of the iPhone is the fact, that e-mails are replied from the device (most people expect it this way, I know). But when it comes to HTML it results in a ugly reply with missplaced pictures and random fonts and sizes etc.

Sometimes I use a Palm Treo 750 to forward bigger attachments instead of my desktop computer, even if I am sitting in front of it. Everything stays 1:1, the speed of sending is like sending a SMS, no matter how big the body and attachments are.

My Question:

As far as I know "Mail for Exchange" is much more clever than this and interacts the Ex2k7 similar to ActiveSync on WM devices. So: what's the deal with the N900?

OK. Now I can confirm this bug and confirm that it is fixed in the sw. update. So, wait for the sw. update.

Meanwhile the workarounds:

1) Use "Send immediately"
2) Send the mails manually pressing the "Send & Receive" button from mail client.

Sounds as an idea for Maemo 6 for me. Will forward it to our responsible guys.

Check the very first message of this thread, pls: http://talk.maemo.org/showpost.php?p=393019&postcount=1

This is pure marketing question. Can not answer it here as it is out of my competence. Regarding N900 working with Exchange 2003, the answer is here: http://talk.maemo.org/showthread.php...&highlight=MfE Can not tell more, sorry.

This is different issue from the issue described in the post http://talk.maemo.org/showthread.php...945&post426945 And it was confirmed here: http://talk.maemo.org/showthread.php?t=35136