I use my email account for Github notifications, but recently they stopped working and I missed many notifications.
Looking at my Gitub account, It said my mail was undeliverable and unverified. So I re-verified my email address and received the verification email successfully and clicked on the link to verify it. But soon after that the meial address became unverified again.
I asked Github for any email header logs and they sent me a partial log that indicates that the plusnet servers consider the github notification as " Message contains spam or virus or sender is blocked "
I have added email@example.com to my whitelist, but they are still not coming through.