Sendmail : STARTTLS=client, relay=[127.0.0.1], version=TLSv1.3, verify=FAIL

Help Aide (en français)
7

???

That’s

  • not paxtour.net, it’s mail.paxtour.net
  • a Sectigo certificate
  • a certificate of your hoster, so the domain name must be wrong

So you have used the wrong domain name, so the result is expected.