[CentOS] user names

Tue Jun 2 06:05:03 UTC 2020
Gordon Messmer <gordon.messmer at gmail.com>

On 6/1/20 10:29 AM, Jerry Geis wrote:
> The problem is the client program trying to talk to the linux server
> is base64 encoding the entire email address for the AUTH LOGIN,
> not just the "username".   so my user name needs to include the "@" symbol.


That's a common requirement for servers that implement multi-domain 
hosting.  In Courier MTA, you can host virtual users in a "userdb" file 
or SQL DB (or LDAP):

https://www.courier-mta.org/FAQ.html#virtual

Postfix supports similar setup:

https://www.howtoforge.com/virtual-users-and-domains-with-postfix-courier-mysql-and-squirrelmail-debian-wheezy

Whether those are options may depend on how invested you are in 
sendmail.  If you're not a sendmail expert, you're probably better off 
using a different mail server.