If you want to be sure that you will not miss e-mail from specific senders, click on "Spam Filtering >> WhiteList " tab under your Plesk home Page, and then add e-mail addresses or entire domains to the spam filter's white list.
To enable whitelisting of email addresses please follow the following steps:-
1) Click on Spam Filtering.
2) Click on "Whitelist".
3) To add entries to the whitelist, Click Add Addresses.
4) If you have a list of entries stored in a file, click Browse to specify it, and then click "OK".
Otherwise, select the "From List option", and type the e-mail addresses into the E-mail addresses box. Place each address in one row, or separate addresses with a coma(,) a colon(;), or a white space. You can use an asterisk (*) as a substitute for a number of letters, and question mark (?) as a substitute for a single letter.
For example: address@yourdomain.com, user?@yourdomain.com, *@yourdomain.com. Specifying *@yourdomain.com will add to the white list all e-mail addresses that are under the yourdomain.com mail domain.
5) Once you are done with the above steps, then you need to switch on the "whitelist" service.
