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Microsoft Exchange ActiveSync Event ID: 3005 ... HTTP status code: [503] how to resolve?

I have one Exchange server installed with Microsoft Exchange server 2003 Service pack 2 [ Build 7638.2].  I have setup this server about 9 month ago and it works well with outlook users.

Most of time it's working fine with IPHONE users, but start about 2 month ago, some time IPHONE users get error message and could not get the emails in. Usually wait for 5 to 10 minutes it gets back to normal. The worst case may take about 2 hours. The IPHONE 4 users also have issue that the emails re download.

From the server event log, I see constantly blow error message. I notice that even when my phone works well (from iphone view) it still generate this error message. I also tired change the settings of IPHONE (push, fetch, etc,)but still same thing. It sounds like every time when IPHONE talk to the exchange server will generate this error message. Some time IPHONE user didn't notice and can get all emails, but some time IPHONE gets error message and email stop downloading especially when more emails need to be downloaded.

Event Type:      Error
Event Source:      Server ActiveSync
Event Category:      None
Event ID:      3005
Date:            3/9/2012
Time:            3:22:19 PM
User:            xxx\yyy
Computer:      abc
Unexpected Exchange mailbox Server error: Server: [] User: [] HTTP status code: [503]. Verify that the Exchange mailbox Server is working correctly.

This question is similar to question:

But I already did what it mentioned but still no luck.  I followed those instructions when I setup the server at the first time.

The most of time the IPHONE users are OK, just this constantly error message shows up. When user is having the issue, then the more error messages are generated. This message can be generated 3 times in a second. So I think if I can fix this error message, it may fix the IPHONE users email downloading problem.

I spent many hours on this and tried different things I can find online but still did not fix it. I hope the expert here can fix this.

Thank you in advance.
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Alan Hardisty
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Try the method 2 from :

Why?  It isn't necessary to create the exchange-oma virtual directory unless FBA is enabled and if it were enabled and the exchange-oma virtual directory didn't exist, then Activesync wouldn't work.

Please stop making rash suggestions.
It's not a rash suggestion. I've seen it working before though in this case the problem may be server performance because the 503 is access denied.

The idea was to create a new oma vdir from of "changes", this can easily be undone.

Very nice article you wrote, by the way.
A 503 error is a service unavailable error not an access denied error.

KB817379 is only relevant if you have FBA enabled on an Exchange 2003 server (not part of SBS) which forces SSL on the Exchange virtual Directory.  As the Activesync virtual directory has SSL by default and the Exchange doesn't, when you enable FBA - you have to create the Exchange-OMA virtual directory with SSL disabled to make activesync work, but you don't get 3005 errors if you don't have the Exchange-OMA virtual directory with FBA enabled.
You're right, 503 is service unavailable.

And, thanks for the detailed explanation on 817379... very enlightening and full of sense.

Thanks for this :)

( Always learning :) )
That's the beauty of EE - it helps polish your existing knowledge and adds to it too :)
So very true !
Kindly refer below link

it works fine, i tried & it work fine
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Thanks everybody, especially to alanhardisty. I have read your amazing article and checked the IIS settings. The only thing difference I can find is ASP.NET version of Exchange virtual directory. Mine is 2.0.50727 and it is i gray color not changeable.

The other thing I find is my LAN Adapter Binding order is incorrect. I have changed it. Once I made this change, the errors gone, I though it is fixed. But after about 40 minutes, I saw the same errors in the event log again. I will check with users if they still feel same or got better.

Thank you again!
Do the users who this error appears for have an email address for your default domain (e.g., user@domain.local) in their email addresses?

Sometime this can cause such issues.
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Unfortunately the problem is still there. I got the error twice yesterday from my IPHONE4 and my manager was having the same issue about 3 times on Sunday. "Server error, contact your system administrator". I have checked my iPhone many times, 90% of it worked well.

We all have email address for the default domain.
Then you may have mailbox issues which need the store to be taken offline and repaired, defragmented and integrity checked:

eseutil /p

eseutil /p

isinteg -s servername -fix -test alltests
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I am thinking if something wrong with the information storage, the outlook will have error too, but no any complain for outlook users.
Not necessarily.
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My priv1.edb file is about 130G big. I checked this article, it says "the repair runs at approximately 4 to 6 gigabytes (GB) per hour, and you must run the Isinteg process after the repair, which runs at approximately 3 to 6 GB per hour. "

"AND: Some real-world data from my test environment here -running eseutil /p on a 100GB EDB took 98935.703 seconds (~ 27 hours) which came to approximately 3.5GB/hour."

I don't think I can find a 30 hours maintenance window to do this.

The article suggested "In almost every circumstance, it is faster and more reliable to restore from a backup than to perform a hard repair on the database. ”

Should I do a full information store backup and then restore from it?


Can you move a user who is seeing the errors to another database then please.
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That's a good idea. I am going to create a new store and move my account to it.
It beats the heck out of repairing 130Gb !
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I moved my mailbox to a new store on a new virtual disk. I setup a new IPHONE 4 accessing my mailbox. The first time I tried to get email, I got "Cannot Get Mail The connection to the server failed" Then wait for a while, I tried again and did received my emails.

Then I checked the event log, there are lots event 3005 error logged. The error message is exactly the same. Unfortunately the problem is still here.
Okay - thanks for trying.

Can you please upgrade your massync.dll and then monitor the logs:

I have the file if you don't want to contact Microsoft for it.
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Please send the file to me chengh[2]  
Once I got the file and replace it, do I need register it manually?
Thank you.
No need to register it - the patch takes care of it.

Will send it over in a sec.
On it's way - please let me know if you don't get it.
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I followed but no luck.
I found the Form based authentication is not working. Is this related?
It could well be.  If you can disable FBA and then delete the Exchange-OMA virtual directory and the registry key (as per KB817379), then run iisreset and test on your devices please.
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I delete the registry key but could not delete exchange-oma virtual directory. There is no delete menu item in the right click menu. I can see delete item from the Exchange virtual directory right click menu. How can I delete exchange-oma virtual directory?
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All phone stop working after I deleted the registry key ExchangeVDir, I had to recreate it. Then phone start working, but 3005 event error keep showing as before.
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Finally it's fixed. It turns out the problem caused by the IIS setting of "connection limited to 50".  Changed it to unlimited fixed the issue. I can not remember who or when it was set to 50.
Interesting fix - that certainly isn't the default value - but more ammo for my article.  Thanks for posting the fix.

Hi all, an update to this specific issue as of Sept 2012.

Our client has an SBS 2003 fully patched as at Sept 2012. ActiveSync 3005 with http 503 errors started hitting the App EventLog every 30 seconds or so for every iPhone after recently updating to IOS 6. Not sure if IOS 6 update is related to the cause, however the 3005's started logging the following day after the update, with no other changes to the server. OWA was also reporting the same http 503 error.

Went through the various (excellent) IIS configuration check posts available here and on the Internet to no effect.

We found the (excellent) MS Remote Connectivity Analyzer (MS RCA) test website to be an  easy way to troubleshoot Exchange ActiveSync errors and here is the link:

In our case, this MSKB article fixed the problem: (see the section entitled "See if a registry key that exceeds 259 characters exists in the HKEY_CLASSES_ROOT registry hive").

As per other posts on the Internet, getting the HKRCScan tool can be the hardest part of the process, but (like others) I found it here:

Run the tool from a DOS box until no errors are reported. Registry editing may be required depending on the issue(s) found, so the usual precautions should be taken before undertaking any changes.

In our case, as no registry editing was required, just restarting the MSEX System Attendant (and Info Store) services stopped the 3005 event logging and most iPhones started syncing again (plus OWA was okay and MS RCA also tested okay).

For the couple of IOS 6 iPhone 4S's that were still getting the dreaded "Cannot Get Mail" error, reducing the number of messages in (any) Outlook/Exchange folder to be synced (including Inbox & Sent) to around 500-700 got push working again (don't ask why?!).
Thanks for the info lexrx - not ever seen the HKCRSCAN tool fix that - but then I've never tried.

I have a copy and will run it on a server that I know has the problem with 3005 errors and see if that discovers anything and will update my article if it does.