Update smtp_provider.md
Update smtp_provider.md

Removed links to ANCIENT blog article.
jacobmovingfwd/docs,katieporter/docs,katieporter/docs,katieporter/docs,hardikjain29/docs,sendgrid/docs,ksigler7/docs,Aonepathan/docs,hardikjain29/docs,jacobmovingfwd/docs,Aonepathan/docs,Aonepathan/docs,Zaftula/docs,jacobmovingfwd/docs,jacobmovingfwd/docs,katieporter/docs,Zaftula/docs,Zaftula/docs,hardikjain29/docs,hardikjain29/docs,Whatthefoxsays/docs,Whatthefoxsays/docs,ksigler7/docs,sendgrid/docs,sendgrid/docs,jacobmovingfwd/docs,Zaftula/docs,Zaftula/docs,ksigler7/docs,Aonepathan/docs,Whatthefoxsays/docs,hardikjain29/docs,katieporter/docs,Aonepathan/docs