Solution for ActiveSync Issues with SupportID 8600050D and EventID 3005.

I just could not believe it, how activesync issues with SupportID 8600050D and EventID 3005 have put very bad psyco impact on IT confidence. To find the cause of this error message:

"there has been a change on your server that requires you to re-synchronize all
items on your device. all changes made since your last successful sync will be
lost do you wish to continue?"

was a real pain in the a*s. The problem is vast and pervasive. Google it up, you will find these isssues all over the world. I wrote the anatomy of the issue in detail at ActiveSync error, now are you ready to get very miserable? . You know what, it took me 6 months to figure out the solution.

These are basically what to do to resolve it, not in detail. Back up your server including the mailboxes bofore doing this:

1. Backup all your users' mailboxes. Convert it to PST files so they still be able to access their previous emails locally. Also keep the backup in your server. I know this is tough and will harvest complain. But you've gotta do what you've gotta do, that's a professional call.
2. Istall the PST files to your users Outlook, test them all before kissing the OST files good bye. Make sure the OST files are gone. You must be aware that using Exmerge to fetch PST out of Exchange has problems with files more then 2Gigs. So google up to mock around this issue. I am not gonna detail it for you.
3. Make sure your Exchange Back-End server is routable. It means you are gonna use Public IP for this. Make sure your firewall configured real well for God's sake. Yes, for God's sake, because if anything happened (like an intruder formatting your drive) to your Exchange Back End server and you don't care for God's sake then He might not care for your sake. And believe me only He can help you with that.
   To make your Back-End server routable, you might need the help from your Internet Access Provider. That depends on your topology, but mostly you will need their help.
4. Make sure your DNS is correct. Make sure you have complete MX and PTR records.
   
5. Recreate the CA Certificate at your Font-End server. This step is mandatory, it is very important to have new certificate. Make sure you inform the whole people on remote are to reinstall the certificate in their machines later on, otherwise RPC-over-HTTP connetion between outlook and exchange won't run.
6. Restart Front-End and Back-End Exchange server.

That's it, mate. Your PushMail through ActiveSync is now working. Yes we need more than 2 days to fix that. As you know the steps above are not in details, I am sure you can break them in details yourself.

- Zep