Recently I've had a few clients on a server having issues with a blacklist. I've been googling for about an hour and am a little tired of it, but maybe someone here can help me.
What do blacklists take into account when blocking mail? Typically when people talk abount sender reputation, they are referring to an IP address. However a bounce back that I'm getting is specifically stating that they won't accept the mail due to the name servers used by the domain. So do blacklists also block an a per NS basis as well as an IP basis?
Any information on this would be appreciated.