Well we don't support other company's here.
This is a forum for Directadmin license holders, so admins (and resellers) not hosting customers.
You should contact bludomain3.net or their hoster, they would know why the mail stopped working, who knows they stopped the mailserver or whatever.
If they would use DA, it would be as simple as using mail.domain.com for incoming and outgoing mail, ofcourse replace domain.com with their domain, nothing to it.
Username is the mail address and then you need the password. That's all to it.
If that don't work, you have to contact their host some way or another. DA can't help you with that, neither can we as users.