Why does this message get marked as spam? What does the AWL mean?

What is the AWL?

Reply:

AWL means Auto whitelist, that doesn't necessarily mean that the sender is whitelisted. The AWL check tracks scores from messages previously received and adjusts the message score, either by boosting messages from senders who send ham or penalizing senders who have sent spam previously. This not only treats some senders as if they were whitelisted but also treats spammers as if they were blacklisted. Each message from a particular sender adjusts the historical total score which can change them from a spammer if they send non-spam messages. Senders who are considered non-spammers can become treated as spammers if they send messages which appear to be spam.  More details here: https://wiki.apache.org/spamassassin/AwlWrongWay
In this particular case I think the best thing to do is whitelist the sender's email address