Cannot send email using our domain hosted by GoDaddy for the last week, no problems sending email on other gmail account

no problem receiving mail on the btadv.com domain hosted by GoDaddy but cannot send on this domain.  Getting the error message smtp starttls command failed.   this probably started after the most recent update although i can’t recall if I installed a recent update?

Hello,

Could you please go to Menu ->Tools -> Accounts - open your account, go to the SMTP tab and change the Security policy to “Use SSL/TLS on special port (legacy)”? Please also make sure you’re using the 465 port.

Thank you,
Maurice