Create email_authentication.md
Create email_authentication.md

Doc 241   User Guide Glossary entry
Ranhiru/docs,sendgrid/docs,GilUpstream/docs,bogdanboss/docs,bogdanboss/docs,awwa/docs,katieporter/docs,hardikjain29/docs,Zaftula/docs,hardikjain29/docs,ksigler7/docs,hardikjain29/docs,katieporter/docs,Whatthefoxsays/docs,taz77/docs,taz77/docs,jacobmovingfwd/docs,bogdanboss/docs,taz77/docs,katieporter/docs,Zaftula/docs,awwa/docs,sendgrid/docs,bogdanboss/docs,GilUpstream/docs,Whatthefoxsays/docs,Zaftula/docs,Ranhiru/docs,GilUpstream/docs,Zaftula/docs,hardikjain29/docs,katieporter/docs,bogdanboss/docs,jacobmovingfwd/docs,jacobmovingfwd/docs,L2G/docs,Aonepathan/docs,GilUpstream/docs,L2G/docs,Zaftula/docs,jacobmovingfwd/docs,L2G/docs,Aonepathan/docs,GilUpstream/docs,Ranhiru/docs,ksigler7/docs,hardikjain29/docs,jacobmovingfwd/docs,taz77/docs,Whatthefoxsays/docs,katieporter/docs,sendgrid/docs,L2G/docs,L2G/docs,ksigler7/docs,Aonepathan/docs,awwa/docs,Aonepathan/docs,Aonepathan/docs,awwa/docs,Ranhiru/docs,taz77/docs,awwa/docs,Ranhiru/docs