Member can't email members group from his primary email address

Hello! Member Mack Miller has 2 emails in his profile. He tried to email our members list (members-1713@toastmastersclubs.org) from his Primary Email tm.mackmiller@gmail.com, but it didn't send. However, sending worked from his Secondary Email mack.miller@comcast.net. Attached img is his Member Profile.

What are we missing? Thanks in advance for your help and all that you do to provide and maintain this platform!

Regards,
Sandy Pon
#1713 President's Club Toastmasters
 

I don't see anything missing. His address is clearly valid as the FTH email logs show email from officers-1712@ and members-1713@ successfully going to his Gmail address. As well as agenda@ going to both of his addresses as it should by his email preferences.

Was there any type of warning or failure notice? Did he attempt this more than once with the same result?

Ask him to check if his Gmail account has an active 'send mail as' address in his settings.