On 04/30/2016 08:56 PM, Gordon Messmer wrote: > On Sat, Apr 30, 2016 at 12:44 PM, Alice Wonder <alice at domblogger.net> wrote: >> >> For e-mail sent to people, yes. >> >> But for what usernames are allowed when creating an account, I don't see why >> blacklisting characters that are not allowed in a username is a standards >> problem. > > > That's not how the RFC rules are defined. But, rather than argue that > point at length, I'd point out that Open Group standards for usernames > are simple and will comply with the SMTP RFCs: > http://pubs.opengroup.org/onlinepubs/000095399/basedefs/xbd_chap03.html#tag_03_426 > > That is, [A-Za-z0-9._][A-Za-z0-9._-] > _______________________________________________ > CentOS mailing list > CentOS at centos.org > https://lists.centos.org/mailman/listinfo/centos > I think there is a mis-understanding. All I was looking for was if there was a common set of characters typically blasted from new usernames *on the domain being set up* I have no desire to refuse delivery to any valid e-mail address. For example, avoiding spaces in usernames for addresses on the system is handy because it avoids bugs where the path to the mailbox on the filesystem isn't properly quoted. So user names on the system won't be allowed to have spaces even though they are legal when within quotes or escaped. That's all I was looking for, was experience on what legal characters to avoid allowing users to have for the mailbox portion of their e-mail address, the username. Of course I have no desire to restrict who they can send to if it is a legal address.