Start with the requirement
Choose based on sender identity, recipient scope, client capability, network constraints, volume, and who will operate the solution.
Update the client
When the client supports OAuth for SMTP or Microsoft Graph, use that native capability first. It removes the need for a compatibility bridge.
Use Microsoft infrastructure
SMTP relay, Direct Send, High Volume Email, and Azure Communication Services Email each solve different sender, recipient, network, and volume scenarios.
Use a focused bridge
smtpify365 is intended for low-friction migration where authenticated SMTP is the only practical interface and mail should continue through a specific Microsoft mailbox.