Is it possible to change an e-mailadres of a guest in Groups

[André Maas]

Can a group-owner change the e-mail address of a guest, when the guest has a new e-mailadress?

[#2]

Yes, Guest users are represented by a mail user objects in the directory so you can use the relevant Exchange cmdlets. For example:

Set-MailUser alias_of_external_user -WindowsEmailAddress newaddress@domain.com

[#3]

Oh sorry, I'm not the tenant owner! I can not use; Exchange cmdlets

Is it possible in the group in Usermanagement, where I can also add users/guests?

[#4 · Accepted solution]

Nope. What you can do is remove the Guest user and add him with the new address.