I have setup a Website based on HTML with the exception of a contact.php page. I am hosting this website on my Rasberry Pi 3 computer on Debian flavor of linux Jesse Light. This is headless as it hosts my Portfolio website. I am using Apache2 webserver and installed sendmail as my Mail Transfer Agent (MTA). The problem is I have been spinning my wheels researching for the past week and I am stuck.
My issue is I send email from my php contact page on my live server but nothing ever arrives in my inbox after sending it. I get a mail sent message from my php script after about a minute after sending but then Nothing arrives in the inbox. I am thinking My SMTP on my php.ini is not correct. I put my website domain name FQ name. I am using Microsoft Exchange Online hosted email domain by GoDaddy. Also, anyone have any good advise on what my from / to should be set to on my SMTP configurations?