You can export a list of all groups with the field mail enabled by running the following code:
$list = Get-ADGroup -Filter * -Properties * | Where {$_.mail -ne $null -and $_.GroupScope -match "Global"} $list | export-csv -Path Globalmetmail.csv -Delimiter ";"
To find groups inside a certain OU for example if you have a distribution OU you may want to export certain Grouptypes:
$list2 = Get-ADGroup -Filter * -Properties * | Where {$_.CanonicalName -match "Distribution" -and $_.GroupScope -match "Global"} $list2 |export-csv -Path GlobalEnInDistributionOU.csv -Delimiter ";"