We had an interesting problem while I was on holiday. (Why doesn't this stuff ever happen when I'm there?) The sysadmin upgraded our Exchange server to Exchange 2010 and everone's subscriptions stopped. My Subscriptions showed an error message saying that the email address of one of the recipients is invalid. When you create a subscription, Reporting puts your Windows user name into the To field and most users have no permissions to edit it. By default, Reporting leaves it up to exchange to resolve that into an email address. This only works if Exchange is set up to translate aliases or 'short names' into email addresses. It turns out this leaves Exchange open to being used as a relay so it is disabled out of the box. You now have three options:

1. Open up Exchange. That would be bad.
2. Give all Reporting users the ability to edit the To field in a subscription. a) They shouldn't have to, it should just work. b) They don't really have any business subscribing anyone but themselves.
3. Fix the report server to add the domain. This looks like the right choice and it works for us. See below for details.

Pre-requisites:

• A single email domain name.
• A clear relationship between the Windows user name and the email address. eg. If the user name is joebloggs, then joebloggs@domainname needs to be the email address or an alias of it.

Warning: Saving changes to the rsreportserver.config file will restart the Report Server service which effectively takes Reporting down for around 30 seconds. Time your action accordingly.

Edit the file rsreportserver.config (most probably in the folder ..\Program Files[ (x86)]\Microsoft SQL Server\MSRS10_50[.instancename]\Reporting Services\ReportServer). There's a setting called DefaultHostName which is empty by default. Enter your email domain name without the leading '@'. Save the file. This domain name will be appended to any destination addresses that don't have a domain name of their own.