You can maintain a personal whitelist to make sure that important clients and other contacts will never be blocked (even if they send you spam). You can also maintain a personal blacklist to block messages from specific addresses and servers (even if they send legitimate email).
When it comes to whitelisting the preferred options is whitelisting an IP address. Whitelisting entire domains or even just an email address can be dangerous. When a domain is whitelisted all email from that domain will bypass spam filtering and be delivered directly to the recipient. This could potentially allow spoofed emails to reach your inbox. For example, an email that looks like it is from paypal may actually be from a spammer trying to steal your login info.
Whitelist best practice:
You can create a personal "blacklist" to block email from specific sources. It's useful for blocking email that we would not consider to be "unsolicited bulk email" and thus not blocked globally by us. For example, you might want to block:
Please do not blacklist spam that is making it past our filters. Instead, send a plain text message including the complete headers and message source of the spam to us. That will allow us to investigate why the email made it past our filters and find the best way to prevent it from happening again for not only you, but for the rest of our customers.
If you are adding multiple entries, a specific format must be followed.
It expects a list, separated by linebreaks in this format:
< Email Address >;< Comment > < Email Address >;< Comment >
Example:
news@example.com;My Newsletter store@example.com;My Online Shop
IPs are configured the same way:
< IP Address >;< Comment > < IP Address >;< Comment >
Example:
10.0.0.1;My Newsletter 10.0.0.2;My Online Shop
We recommend checking into any IP before adding it to your whitelist or blacklist.
You can whitelist or blacklist all email addresses at a specific domain by specifying just the domain with the at (@) symbol in the "E-mail Address" text box.
For example, to allow any email address from example.com, you would enter "@example.com" (without the quotes).
It is very important to determine the IP address of the organization's mail server to be blacklisted or whitelisted. This can be done by examining the headers of e-mail messages from the organization.
Once you have the IP, go to www.dnsstuff.com and enter the IP address into the IPWHOIS Lookup box. This will tell you what country this IP address is assigned to and sometimes the name of the company that owns the IP address. This will help you decide if you should blacklist or whitelist the IP address.