The issue here is that when sending an e-mail from a hostgator account, it would be delivered after more than 6 hours.
After talking in the chat with hostgator support, they said that the issue was: “It’s an issue with the connection to the exim server to our outgoing firewall.”.
Not much to say, they might fix it for now, but it could happen in the future.
I told them in the chat about this issue from 2008 with e-mails being stuck in a queue: http://forums.hostgator.com/e-mail-delays-t27097.html.
But they said that is old stuff and it was already fixed with so many updates through the years.
Hostgator doesn’t offer support by e-mail or tickets. However, you can send your concern and feedback to this e-mail address: firstname.lastname@example.org.