550 High probability of spam on all Confirmation Email to purchaser with Siteground

It was kind of you to help me Shop Suey!
I changed configuration-E-mail options - E-mail transport method to smtpauth.
I verified smtp email mail server port matched siteground's #.
I verified smtp email mail host and smtp email account password.
It now works perfectly without all of the extra characters previously found in the 'message headers' of the emails in Webmail.

Problems can be had with both methods if you do not have valid SPF, DKIM, and DMARC settings.

Discussion at - https://docs.zen-cart.com/user/email...dkim-and-dmarc

Check your site at - https://mxtoolbox.com/