How to find a UMUser with a particular extension

To find a UMUser who has a extensioni “xxxx” using powershell

get-ummailbox | where { $_.Extensions -eq “xxxx” }

and

get-ummailbox | ForEach { If($_.Extensions -eq xxxx){$.DisplayName}}

To find a UMUser who has a extensioni “xxxx” using powershell

EMC and use a filter for email addresses using either contain or starts with method. Then in the filter use EUM:xxxx