What is a blacklist? It is a question I actually had to answer to one of my clients this weekend in regards to their personal email address. What is a Blacklisted email address? A blacklist is a list of servers or domains that a blacklist operator has deemed it sends spam emails although not all blacklists are created equally. Smaller blacklists such as Spam Cannibal and NoSolicitado usually have less of an impact overall but some – such as SpamHaus and Barracuda – are well known and can be very powerful. The impact that a blacklisting has on “deliverability” depends on a number of things but mainly the recipient server subscribing to the blacklist. How does a blacklisting happen? If for example one of our customers sends an email campaign to a data-list he has bought or has scraped, or third party contacts (or even is simply very old) on that…