Blacklisting an email is determined via a policy, that is normally based on how many emails are been sent from that email address. These policies are managed by different vendors all over the world, which email server admins may subscribe to, in order to help protect their servers.

If you have received a bounce back email from an email address you have tried to send to, it is likely the server or your email address you’re sending from has a poor reputation, with the bounce back containing more information.

Removal of your email address off of these blacklist is an automated process, with the Slingshot staff having limited ability to fix the issue.

As blacklisting normally happens when high volumes of spam are sent, you can help reduce risk to your account and to the mail service by ensuring you have a strong password and by keeping it secure.