Can I use "email@example.com" instead of "firstname.lastname@example.org" in from and reply to addresses?
Mailbox configuration, all versions
We suggest that you always use the full domain name when setting mailbox Reply To and From addresses to a current hosted server address. This applies to both Service and Outreach mailboxes.
We also suggest that you change any old pod names such as mailuk, maileu, mailnj to the name of your current pod name. Often times mailboxes are not reconfigured after a pod migration.
While we do have redirects in place to handle mail sent to an address without a subdomain, such as @custhelp.com, it is not suggested to rely on those addresses. Always use the full name or mail may be directed to a pod that is in a different physical location than the one on which your site exists. Then the mail may be filtered by the default settings in the spam filter on that pod.