Form submissions are NOT spam but CF7/Akismet think they are

I use Contact Form 7 for event RSVPs. One member has been complaining for 10 months that he is told he is spam regardless of which of his 2 or 3 email addresses he uses. But he couldn’t explain and I didn’t see this.Using Flamingo now, I see that all of this guy’s form submissions are marked as spam.

I am using Akismet in CF7 this way:

First name (required)
[text* first-name placeholder akismet:author "First name"]

Last name (required)
[text* last-name placeholder akismet:author "Last name"]

The question is: How do I get him to NOT be spam. How do I whitelist him or add him to the Flamingo Address Book? I see no way to do either. Not in CF7, not in Flamingo, not in Akismet.

I have tried WordPress Discussion Settings but there is only a blacklist there, not a whitelist.

Any advice/pointers/tips are very welcome.