Currently Virtualmin reserves the following 3 names (possibly more?) which can not be used as usernames or email address names: "logs", "virtualmin-backup", and, "domains".
I understand the need for reserved names in order for internal use by virtualmin but I believe "virtualmin-" should have been appended to "logs" and "domains" just like it was to "virtualmin-backups".
"logs" and "domains" are very commonly used addresses and having virtualmin reserve these names is a turn off for people looking to switch from other control panels to virtualmin where the user already has email addresses such as "email@example.com". I'm in the process of converting a clients setup from cpanel to virtualmin and this person uses a "firstname.lastname@example.org" email address as the business contact for all his domain related logins (registrars, ssl certificate providers, etc...) as well as the SOA email for more then 1000 domain records.
Having to change all this because virtualmin reserves the "domains" name is a major hassle that could be avoided if Virtualmin just used "virtualmin-domains", "virtualmin-logs", for internal use.
I will mark this as low priority but i believe it is still a feature that would benefit people.