In Zimbra, imap usernames are in the form of the account name with domain name and a @ character in between.

Is there alternative delimiter characters between account name and domain names available?

I have a customer using an older eudora email client. Eudora accepts user name and server in one single string of text in the form of account@mailserver. The client fails to connect, probably because of two @-characters. On older email server, the imap server was configured to allow # and / as delimiters.