SMTP2GO

SMTP2GO takes two credentials: an API key for its API, and one of its SMTP users for the relay. Its webhooks report what happened after the handoff — deliveries, bounces, spam reports, and rejections — which powers the delivered state, webhooks like mail.delivered and mail.bounced, and automatic suppressions.

Before you start

• An SMTP2GO account with your sender domain verified — see Deliverability for what each record proves.
• For the API transport: an API key (Sending → API Keys → Add API Key) with permission to send (/email/send).
• For the SMTP transport: an SMTP user (Sending → SMTP Users) — its own username and password, not the API key.

Add the account in Mailway

1. Add the provider.

   In the console, open Providers → New provider, pick SMTP2GO and paste the API key and the SMTP user’s login. Mailway relays SMTP mail over mail.smtp2go.com on port 465 (implicit TLS), and sends API and console mail over SMTP2GO’s API. Secrets are encrypted at rest.

   Tip

   Keep the SMTP user’s login and leave Send via on Auto. Without it (or set to API only), relayed mail can’t be handed over as-is, because SMTP2GO’s API is structured-only. It then skips the account unless a project admin enables re-encoding on the attachment.

2. Attach it to a project.

   Open the project, attach the provider, and position it in the failover order.

Delivery events

Without delivery events, SMTP2GO only reports that it accepted the mail. With them, SMTP2GO tells Mailway what happened afterwards.

1. Open delivery tracking. In the console, open the provider → Delivery tracking (beside Configure). Mailway creates the provider’s webhook URL. SMTP2GO’s form takes one Authorization header value, so Mailway also generates a login and shows it ready to paste: the Authorization value (the base64 of username:password). The URL and the value are secrets; treat them like passwords.

2. Add the webhook in SMTP2GO. Settings → Webhooks → Continue → Add Webhook:

   • URL: paste the URL.
   • Authorization header: Basic, and paste the Authorization value into the field beside it.
   • Users: all users selected. Output type: JSON (form encoded works too).
   • Email events to include: Delivered to recipient, Bounced, Marked as spam, and Rejected. Email processed, Opened, Link clicked, and Unsubscribed/Resubscribed can stay off.

What each event does in Mailway

SMTP2GO event	Mailway outcome
Delivered to recipient	The mail turns delivered (confirmed by the provider’s event).
Bounced (hard)	The mail turns bounced; the address is auto-suppressed for the project.
Bounced (soft)	Recorded as soft_bounced (temporary; a later delivery outranks it).
Marked as spam	The mail turns complained; the address is auto-suppressed.
Rejected	Recorded as dropped: SMTP2GO refused it, typically for an address it already suppresses. The mail keeps its state.

Note

Events correlate through the email id SMTP2GO returns — at the API handoff, and in the 250 OK id=… reply of its SMTP relay — with the Message-ID header SMTP2GO echoes on every event as a second key. An event only ever affects mail your own team sent through that provider.

Check the connection

• Connection check. The provider page’s connection check logs in over SMTP and asks SMTP2GO what the key may do, without sending anything — it tells you if the key lacks the send permission.
• Delivery events. Save changes in SMTP2GO, then Test this webhook. The Delivery tracking dialog’s last step waits for that first event and ticks when it arrives.

What SMTP2GO changes

In our tests, mail relayed over SMTP2GO’s SMTP arrived exactly as sent — headers, body, and a DKIM signature your app applied all intact — with tracking and the unsubscribe footer off, which is SMTP2GO’s default. See What providers change.

Limits

• SMTP2GO allows 400 recipients per message, counting To, Cc, and Bcc. Over SMTP, Mailway handles bigger sends automatically — see the fan-out note.
• SMTP2GO’s free plan allows one webhook.
• Otherwise your SMTP2GO plan’s own sending limits apply.