Relevant

Event 3005 from source ServerActiveSync

I receive the following error on two servers I manage. Both servers have been through a swing migration, but I haven't pin-pointed whether this is the problem yet. Client A is using Windows Mobile phones only, and was using these before the migration, unfortunately I'm not sure whether the error messages were present before the migration. Client B is using iPhones only, but they were not set up before the migration.

Log: Application
Type: Error
Event: 3005
Source: ServerActiveSync
Description: Unexpected Exchange mailbox Server error: Server: [sbs.test.local] User: [
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 ] HTTP status code: [503]. Verify that the Exchange mailbox Server is working correctly.

The phones all seem to synchronise without any issues.

An article suggests checking the ExchangeVDir in HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\MasSync\Parameters is set to /exchange-oma rather than ExchDAV, but I checked this and it was already set correctly.

If anyone knows what this is, please lease a comment!