I have SharePoint 2013 configured in a test environment that does not have a mail server installed. I could not use alerts or the mail task in workflows after I configured SharePoint 2013.
This was caused because the User Profile Service Application was trying to sync the Work Email with the AD attribute ‘ProxyAddresses’ and not with the attribute ‘mail’. I used SharePoint Profile Synchronization!
The attribute ‘proxyAddresses’ is normally filled with information given by for example Exchange or Lync. The attribute is <not set> because I don’t have these kind of servers.
Configure the user propertie import for Work Email:
First check if the User Profile Sync Service has started
Go to the User Profile Service Application
click on ‘Manage User Properties’ and navigate to Work Email
Change the below setting:
Start a full sync after changing this setting and the mail addresses will be filled in for users.