Allowed Characters for Mailboxes

If you plan to create a new mailbox in the mailcow Groupware, please note the allowed characters in the local part of the email address (i.e., before the @ symbol).

Recommendation

Use simple, compatible character combinations whenever possible to ensure smooth functionality across various mail clients and systems.

Allowed Characters

abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789.-_@

The characters listed here are currently allowed.
Please note: The @ character must, of course, not appear within the local part – it is included in this list solely for completeness, as it technically marks the transition to the domain part.

Extending the Character Set

If you require an additional character that is not currently allowed, feel free to submit a request to us.
We regularly review whether additional characters can be included.

Please understand that not every special character (if any at all) can be integrated on short notice.
Since you share the mail server environment (hosted.mailcow.de) with many other users, changes to the allowed character set are always approached with caution and extensive testing.
Unconsidered approvals could negatively impact the stability and security of the system.