SharePoint 2013: The following users do not have e-mail addresses specified

Problem

You create a new alert on a list for a group of users.  After configuring the alert, and then clicking OK, you see the following error message:

Sorry, something went wrong 
The following users do not have e-mail addresses specified: 
    -[Person M]
    -[Person N]
    -[Person O]

Alerts have been created successfully but these users will not 
receive notifications until valid e-mail or mobile addresses 
have been provided. 

Technical Details 

Troubleshoot issues with Microsoft SharePoint Foundation. 

Correlation ID: 31fc919d-f366-2064-a6e5-34668d1de1b7 

Date and Time: [date/time]

You then begin troubleshooting.

Troubleshooting

1. Repeated creating the alert: same error.
2. Checked alert membership: Go: Settings (Gear icon) > Site settings > Site Administration > User Alerts.  Cycled through all users in dropdown list: all other users configured for the alert appear except for those shown above.
3. Create alert on mirror development farm instance: same error.
4. Created alert for ad hoc select of users and those listed above: alerts for those users listed above generated error, but all others were created without error.
5. Manually edit user profile with email: Go: Central Administration > User Profile Service > People > Manage User Profiles > [search for last name] > [entered email] > saved.  Same error.
6. Manually initiate new User Profile content Full Crawl: same error
7. Manually initiate new Profile Synchronization: same error.
8. Perform web search on error text: found this posting and others (listed below in References section).
9. Ran this command: Get-SPUser –Web  "http://webappurl" | Set-SPUser –SyncFromAD.  No more error when creating alert.

Solution

• If standard methods fail, run the command in an elevated SMS.

References

• email not working : The following users do not have e-mail addresses specified
• automating the Set-SPUser powershell command
• User Information List not Synchronised with User Profiles
• Syncing WSS and MOSS User profile properties with Active Directory

Notes

• SMS: SharePoint Management Shell.
• When running this commandlet, it may will generate a lengthy error list.  Not to worry: this list is the result of the commandlet not being able to synchronize an account in SharePoint with the an account in AD.  This may be due to the account being a service account, which likely does not have an email address configured for it, or due to the person no longer being a member of the filtered AD group that the UPA connection interrogates.  Thus, I have found this commandlet useful in generating a listing of "orphaned" users.