Email not sending v2.15

Your software
My Mautic version is: 2.15
My PHP version is: 7.0.33-0ubuntu0.16.04.12


My problem is: I use Sendgrid with Mautic 2.15. Friday, I sent and received emails from Mautic and everything worked. Saturday I sent an email twice from different campaigns to my yahoo and Office 360 accounts. The emails were sent by Mautic at 4:00pm, then again at 7:45 pm. There is no record of the email in Sendgrid at 8:15pm. Please help! Thank you, Robin


These errors are showing in the log: No errors show.

Steps I have tried to fix the problem: