Actually, it is frustrating if you are receiving a lot of spam email. Even you have so-called the best anti-spam on your email service, you can receiving spam email, maybe lesser and at the same time, you might treat some emails as spam email, known as false positive.
As far as I’m concerned, there isn’t 100%. With anti-spam you are receiving lesser definitely but your definition is never the same as the server. Some anti-spam require you to set rules or train them in order to be effective
Thus, you cannot eliminate those spam emails defined by you. However, you can still minimise receiving spam emails without spending a lot to or buy a good anti-spam. Here are a few tips to help you;
a. Never use your ‘work’ email to do registration online for personal use, Your email address can be sold to someone for bulk sending. Always think twice if registration is necessary.
b. Avoid common account name like help, sales, enquiry or similar. If your name is John, avoid using john@, and add your last name.
c. Do not advertise your email address. Spammers like to use harvesting technique to collect email addresses. Common areas like auction portals, buy & sell portal etc.
e. Make sure you use SPF in your domain name DNS allows only permitted email server to send an email on your behalf. I recommend ‘-a’ at the end of SPF record if you want to enforce those emails impersonate your organization.
f. Use effective RBLs on your email server. Reputable RBLs filter emails sent from bad IP addresses.