The first question when choosing an email provider should be how your application can connect to it. Some applications accept an SMTP host and password. Others let you make an HTTP request from server-side code. Those are different integration contracts, even when the message looks identical to the recipient.
When an HTTP API fits
An API works well when you control the application code and want structured request validation, a returned message identifier and a documented way to retrieve status. Sendar's public sending integration uses HTTPS and JSON. Your application authenticates with a server-side Bearer key and submits the fields described in the API reference.
This approach gives you a natural place to attach an application event ID, record an attempt and handle HTTP error responses. It does not remove the need for domain verification, recipient controls or delivery monitoring.
When SMTP is the existing contract
A plugin that only exposes SMTP configuration cannot use an HTTP email API just by replacing the server address. It needs an HTTP-capable plugin, a change to the application, or a maintained adapter. Sendar should not be treated as a drop-in SMTP credential replacement.
Before choosing an adapter, check whether it preserves the fields your application needs. Attachments, reply handling, custom headers and failure reporting may behave differently. Also decide who operates the adapter and how its credentials are rotated.
Compare the whole failure path
Imagine that a receipt request times out. Can you determine whether the provider accepted it? Can you associate a returned record with the order? Does the integration offer idempotency for that exact operation? These questions matter more than a successful demonstration message.
With Sendar, single-email API requests support an Idempotency-Key. Batch sending has a different contract and no documented idempotency guarantee. Do not apply one workflow's retry policy to the other without checking the documentation.
Make the decision before migrating
Inventory your current application's transport, template format and status handling. If you can make authenticated HTTP requests, start with a small Sendar proof of concept. If you are restricted to SMTP, resolve that compatibility gap first. A migration plan that names an unsupported dependency early can save a much larger integration rewrite later.