On Wed, Mar 18, 2020, 2:44 AM ToddAndMargo via users <users@lists.fedoraproject.org> wrote:

$ cat mail.txt | curl -vvv smtp://smtp.gmail.com:465 --mail-from
"xxxx@gmail.com" --mail-rcpt "yyyy@zoho.com" --ssl -u
xxxx@gmail.com:'zzzz' -oauth2-bearer 'big long thing' 

Port 465 is SMTPS (SMTP over Explicit TLS). Use smtps://smtp.gmail.com:465 or smtp://smtp.gmail.com:587 for SMTP with implicit TLS.