I'm trying to send an email to someone @uni-duisburg-essen.de, and part of their name includes the character 'ü'. Including that as part of the email address, I getServer error: 'Invalid recipient'
In Gmail, I get the message saying the address in the To: field was not recognised.
Sending the email, replacing ü with u, results in an email back from their email server saying no such user exists.
So how do I send this person an email?