Could they have consciously chosen to remove that functionality?
E.g. to simplify code, or if they wanted all mails to have a domain (if, for example, they wanted to integrate with reputation systems that were domain oriented)?
Based on the incredibly basic bounce message, I suspect the problem is that the frontend eats the address before it even gets to delivery.
To your question, yes any product decision is possible, but enterprise/government people are surprisingly demanding about this stuff working because they have extremely weird requirements for routing mail to and through legacy systems. So I bet this still works at the mailer level and is broken in the UI.
Based on the incredibly basic bounce message, I suspect the problem is that the frontend eats the address before it even gets to delivery.
To your question, yes any product decision is possible, but enterprise/government people are surprisingly demanding about this stuff working because they have extremely weird requirements for routing mail to and through legacy systems. So I bet this still works at the mailer level and is broken in the UI.