Previously, we illustrated how to use the -match operator to find illegal characters in a text. The -match operator finds only the first match, though. To list all illegal characters in a string, try this approach:
# some email address $mail = 'THOMAS.börßen_senbÖrg@test.com' # list of legal characters, inverted by "^" $pattern = '[^a-z0-9\.@]' # find all matches, case-insensitive $allMatch = [regex]::Matches($mail, $pattern, 'IgnoreCase') # create list of invalid characters $invalid = $allMatch.Value | Sort-Object -Unique 'Illegal characters found: {0}' -f ($invalid -join ', ')
The result looks like this:
Illegal characters found: _, ö, ß
