We are planning to upgrade our exchange server from 2007 to 2013 and I have been asked whether its possible to generate a message to all external emails that may email at this time an automated message stating that the server is currently unavailable.  I understand that there is downtime so therefore unlikely.

• Moved by Jason Johnston [MSFT]Microsoft employee Wednesday, June 24, 2015 1:55 PM Not a development question.

Apart from above given suggestion, I would like to refer you on this well described technet article that covers almost all the necessary parts and provides the instructions to accomplish this job flawlessly : http://blogs.technet.com/b/meamcs/archive/2013/07/25/part-1-step-by-step-exchange-2007-to-2013-migration.aspx

Moreover, while need to migrate users mailboxes from Exchange 2007 to 2013, you may also consider on this automated solution (http://www.exchangemailboxmigration.com/) that seems to be a good alternative approach to get migration task done without having downtime or any further interruption.

Sorry forgot to mention we are also virtualising the new server so will have a downtime but thanks will take a look at the link you have provided.  I was also thinking of perhaps being able to edit the standard bounced back message that users get when there is an issue with email

Hi,

If you scheduled a "downtime" with external internet envirnoment in your migration, the external sender would receive a NDR if the message can't be sent to your environment.

Also, the internal message would not be sent to the outside either, including the notification which you required. We can use the Microsoft Exchange Server Deployment Assistant as what Hinte stated to help you do the migration. Additionally, we can refer to the following article to have a start:

http://blogs.technet.com/b/meamcs/archive/2013/07/25/part-1-step-by-step-exchange-2007-to-2013-migration.aspx

Best Re