In addition to above I was still getting this error
echo "Test message from Linux server using ssmtp" | sudo ssmtp -vvv somebody@mil.gov
[<-] 220 smtp.gmail.com ESMTP v193sm19198825qka.18 - gsmtp
[->] EHLO localhost
[<-] 250 SMTPUTF8
[->] STARTTLS
[<-] 220 2.0.0 Ready to start TLS
[->] EHLO localhost
[<-] 250 SMTPUTF8
[->] AUTH LOGIN
[<-] 334 VXNlcm5hbWU6
[->] aG94Z2VuZUBrrrFpbC5jb20=
[<-] 334 UGFzweliecmQ6
[<-] 534 5.7.14 https://support.google.com/mail/answer/78754 v193sm19198825qka.18 - gsmtp
ssmtp: Authorization failed (534 5.7.14 https://support.google.com/mail/answer/78754 v193sm19198825qka.18 - gsmtp)
SOLUTION : do a gmail password reset even when current password is correct ... possibly Google security precaution