7,023 questions
Check the user logon name (UPN) value in AD, sounds like its not configured correctly.
Should be ******@domain.com
If in doubt, clear it and re-enter and then wait a few minutes to see if that error clears in Exchange
Exchange 2016 Mailbox user error "Property expression "user" is not valid"
![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(86.4, 99%, 18%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EIE%3C/text%3E%3C/svg%3E)
IT Engineer
260
Reputation points
Hello,
We have issue with a mailbox user as "Property expression "user" is not valid. Valid values are Strings that includes '@' , where '@' cannot be the last character" message appears in EAC recipients.
Same user has no issue with emails, also active directory account is perfectly configured. However we have noticed, on recipient's page user logon box is empty for effected user.
Cant figure out what exactly the issue.
Windows for business | Windows Client for IT Pros | Directory services | Active Directory
Exchange | Exchange Server | Management
7,920 questions
Accepted answer
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Andy David - MVP 157.4K Reputation points MVP Volunteer Moderator2023-12-31T19:11:15.4466667+00:00 -
IT Engineer 260 Reputation points
2023-12-31T20:44:14.7966667+00:00 UPN configuration is correct. But at Exchange side logon box is still empty. Will it be fine to enter user logon name manually??
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![](data:image/svg+xml, %3Csvg xmlns='http://www.w3.org/2000/svg' height='64' class='font-weight-bold' style='font: 600 30.11764705882353px "SegoeUI", Arial' width='64'%3E%3Ccircle fill='hsl(284.8, 17%, 37%)' cx='32' cy='32' r='32' /%3E%3Ctext x='50%25' y='55%25' dominant-baseline='middle' text-anchor='middle' fill='%23FFF' %3EYS%3C/text%3E%3C/svg%3E)
Yuki Sun-MSFT 41,376 Reputation points Moderator2024-01-01T02:20:50.1433333+00:00 Hi @IT Engineer ,
Agree with Andy that the error is likely to be related to the UPN value in AD. Could you please open the Active Directory Users and Computers and double check the UPN value of this affected recipient? Make sure it has the domain name filled in the domain section:
If it's already correct, as aforementioned by Andy, clear it and then re-enter to see if it can fix the error in Exchange after a few minutes.
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IT Engineer 260 Reputation points
2024-01-02T08:46:36.0633333+00:00 You are right, dont believe how I missed that UPN part, domain was not selected, once we added domain attribute the error from exchange is disappears.
Thanks
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