Guide
Connecting SMTP2GO
Set up SMTP2GO: the API key or SMTP credentials, sender verification, and what it will not automate.
SMTP2GO is the least ceremony of the three relays: an account, a key, and a domain to verify.
The key
Create an API key at https://app.smtp2go.com/settings/apikeys/. The API lets this product read verification status and manage sender identities; SMTP credentials send and nothing else.
Verifying a sender
Add the domain in SMTP2GO and publish the records it asks for. If a DNS provider is connected here, that publishing is a button rather than a copy-and-paste exercise.
SMTP2GO can also send you a setup link for the domain, which is the same records by another route.
What it will not do
Signing keys for its event webhook are not offered, so webhook payloads cannot be verified the way SendGrid's can. Treat that endpoint's contents as a claim rather than a fact: this product corroborates bounce reports against its own send records instead of trusting the payload alone.
Subaccounts exist on paid plans and behave like SendGrid's subusers -- their own reputation, their own compartment.
Sending limits
The plan's quota and this product's warm-up ramp are two different ceilings, and the effective limit is the lower one. A new identity is ramped whatever the plan allows, because a quota is a commercial limit and a ramp is a reputation one.
Full API documentation: https://apidoc.smtp2go.com/documentation/