There are several possibilities here:
You have (perhaps a long time ago) set your e-mail address to “Robinson me”. All personal data have been deleted and the hash of the e-mail address has been tagged as invalid.
Your provider has asked us not to send messages to e-mail addresses belonging to them. We respect this, of course.
Your provider is not offering mailboxes on a permanent basis.
Your provider has rejected our e-mails as “Spam” and has not responded to our requests. Further sending of e-mails is not useful and only causes unnecessary traffic.