When an employee leaves Archetype, his email account is blocked (connection is blocked but emails are still received) and his name is prefixed with Ωyymmdd where yymmdd is the date of his account closure.
Those emails are not listed in the online Global Address Book anymore.
If you send an email to a former employee mailbox, you might receive an automatic reply such as "Please note that this mailbox is deactivated since the recipient left Archetype Group...". This is an internal automatic answer, if someone outside the company send an email to such mailbox, he won't receive this.