Beware possible Email Loss – Dirsync and Unique Circumstances


Recently I had a Unique scenario – this was caused by a need to decommission an old server of mine that was running Server 2008 R2 (and was the only Domain Controller) and upgrade it to 2012 R2 – unfortunately on the existing hardware.

* Spoiler Alert  If possible always virtualise any DC that is either a SPOF or is to be upgraded so that you can in the worst case revert to it if required *

Now as I had to reuse the server I had a few months ago killed off DirSync from the server and carried on with “In Cloud” Identities – which was fine until this weekend when I rebuilt the Domain​ and had a few small changes that I needed to make – Mainly the FQDN of the Domain to remove an unnecessary .com addition (rushed deployment 3 years ago at night – I’ve learnt since then) and a change to the NetBIOS Domain Name – to shorten it.

All in all when I recreated the domain with the right users in the Domain – including the one for my main Email – this started throwing up errors due to the following attributes

  • Mail
  • UserPrincipleName
  • ProxyAddresses

Following an article online in regards to forcing a Cloud Identity to work out that there was an On-Premises replicated object it specifies that you should make sure that if the Online User has an Exchange Mailbox that you set the Proxy Address to be the Email Address for this mailbox

Well I did that – and it failed for almost 3 hours of forced DirSync replications.

So I renamed my Online User’s UPN to one that doesn’t exist in the On-Prem AD so that it would get around this issue and lost a lot of emails (which i should have exported but oh well)

Hopefully you won’t have this happen in your scenarios however this is just a be Forewarned type Blog post.

Thanks for reading 🙂

Published: 06/07/2015 13:30

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