Black lists
I have taken a lot of care in selecting hosting providers where they have systems in place that can detect spam being sent from a server. This means it is unlikely that you can end up on a blacklist. For those of you that have been with me for some time, the previous hosting company (Hostpapa), it used to happen once a month.
In selecting a new hosting partner this was one of the areas where I wanted to reduce the risk of it occurring.
What is a black list?
There are a number of services that monitor mail being sent and receive reports from monitors around the internet. They look for large volumes of mail from the same source (IP Address) on the basis that this may be a hacker who has taken over an account or server. Much of your unsolicited mail comes from sources like this.
Some organisations, in particular local government and government sites, and their agencies subscribe to blacklist checking services.
This means when an email comes into their server (or more likely while it is on the way to the server), a process will check to see where it came from, and perform some checks to establish if the source is listed in a black list somewhere.
If it is then the email is rejected. You will receive a rejection notice normally, although I have seen examples where no response is given. The rejection messages are often written in techno speak (yes, and I struggle sometimes). So not very user friendly.
Check the black lists
If you keep having problems sending emails from your domain to other sites such as council offices then check to see if your domain name is blacklisted. This is step 1.
You can do that by going to here: http://www.mxtoolbox.com
Enter your domain name and click on MX Lookup. When the result comes back click on the Blacklist check link.
The list you get back should all be green. Some may show timeouts. It is not 100% accurate, but if something has happened, it is likely that your domain will be on more than one list.
How do you get off a black list?
Once on a black list, they usually clear in an hour or so. If you find you are on a blacklist let me know. If it is to do with the server in the hosting (some of you source your mail through a third party), I will contact the hosting company and ask for it to be cleared.
What else can I do?
Use a different email address and try to send the same message to the recipient. Sometimes when these events occur they are reported erroneously. In various conversations I have had with technical support they don’t have a clue.
How did I get on a black list?
The chances are that you did not get on it through any action you took. The server is a shared resource, there will be many websites running on it. It only needs another account to be hacked, or someone using their account for illegitimate purposes and this is what triggers it. If someone is found deliberately sending spam out, then they will probably have their account cancelled.
In both of the reseller accounts I use, they employ mechanisms that detect the presence of high volumes of emails being sent and will flag it to the support team. If the volumes are really large (50,000) then I have seen in one case that the email was prevented from being sent. So it never left the hosting.