[CentOS] E-mail advice sought

[Richard]

------------ Original Message ------------
> Date: Saturday, April 30, 2016 12:44:52 -0700
> From: Alice Wonder <alice at domblogger.net>
>
> On 04/30/2016 12:22 PM, Gordon Messmer wrote:
>> On 04/30/2016 11:28 AM, Alice Wonder wrote:
>>> Is there any advice on characters to allow in usernames?
>> ...
>>> I don't think a whitelist alphabet is best approach because of
>>> people with names that are not spelled with Latin characters.
>>> 
>>> Is there an existing blacklist of characters that technically
>>> legal but are generally avoided in e-mail addresses?
>> 
>> The RFC uses a list of allowed characters, and so must you.
> 
> 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.

You can set any rules you want for what your local users can use for
their accounts -- within the constraints of the mail RFCs. You just
have to accept mail with and allow your users to send to any RFC
compliant email address.