Although our SMTP filtering does not allow a specific sender to be white-listed, you can take advantage of our (Old) Email Hyphenated Suffixes feature. Simply create a new email address just for use by that sender, explicitly add that address (see (Old) Adding/Removing Email Addresses), and keep SMTP filtering switched off for only that email address (see (Old) Classic Linux: SMTP Filtering to Keep Out Spam). Then give that sender this new email address and ask him to send mail to you at this email address. Now that sender can send you email, while all your other email is still spam-filtered just as well as ever.
Also please see: (Old) If Legitimate Mail is Blocked.
This document is: http://faq.rahul.net/cgi-bin/fom.cgi?file=50
[Search] [Appearance] This is a Faq-O-Matic 2.721.