Usernames / Emails

When setting up a user for a domain (for the email address) it automatically puts a prefix (web1_ for example).


I think this makes things untidy so is there anyway to remove this prefixing? Also emails aren't working for one domain but they are for another. User can send emails but not receiving any (so need to look at why) but i think it could be todo with the prefixing!


Any way to remove the prefixing of usernames or will it mean there can only be one user called admin on the server? Must be a way to section users for domains without prefixing!?
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