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SETUP GUIDES · MESSAGING

Email with an SMTP service

Send email through the mail service you already use.

⏱ About 15 minutes

Any mail service that offers SMTP works: SendGrid, Mailgun, Postmark, Brevo, Microsoft 365, Google Workspace or your own server. SMTP confirms only that the service accepted a message; bounces come back later as emails to the from address. For high volumes, use a transactional mail service rather than a personal mailbox, which has low daily limits.

Words you’ll see

SMTP
The standard way programs hand email to a mail service. Your mail service gives you a host, a port, a username and a password (often an API key) for it.
DKIM
A signature on every email that proves it really comes from your domain. You turn it on by adding the DNS records SES gives you; without it, mail lands in spam.

Before you start

  • An account at a mail service, with your sending domain set up there (SPF and DKIM as the service describes).

Steps

  1. Find your service’s SMTP settings: SendGrid smtp.sendgrid.net, port 587, username apikey, password an API key. Mailgun smtp.mailgun.org, 587, the SMTP credentials of your domain. Postmark smtp.postmarkapp.com, 587, a server token as username and password. Brevo smtp-relay.brevo.com, 587, your login and an SMTP key. Microsoft 365 smtp.office365.com, 587, a mailbox with SMTP AUTH enabled by your admin. Google Workspace smtp.gmail.com, 587, an app password (2-Step Verification on). Amazon SES SMTP email-smtp.REGION.amazonaws.com, 587, SES SMTP credentials (not access keys).
  2. In the Claspine console open Messaging → Setup, choose SMTP service, then under 2. Connect click Add key on SMTP email service and enter host, port (587, 465 or 2525), username and password. Port 465 uses SSL; the others STARTTLS. Save.
  3. Open Messaging → Setup → Email: provider SMTP service, the from address your service allows, save, then Check my email setup. Claspine signs in to the service without sending anything.
  4. Add a template and send a test to yourself under Messaging → Test.

What goes where in Claspine

Console fieldValue
Messaging → SMTP keyHost, port, username and password (or API key) from your mail service.
Messaging → Email → FROM ADDRESSAn address your mail service lets you send from.

Keep it safe

  • Use a password made for this (an API key or app password), so you can revoke it without changing your own.
  • Claspine connects only to public mail servers on standard ports, with encryption.

Claspine stores the values encrypted, never shows them again in full, and never sends them to your app or SDK.

If something goes wrong

Check says “Sign-in refused”.
Most services need an API key or app password here, not your normal password. Microsoft 365 needs SMTP AUTH enabled for the mailbox.
Check says “Could not connect”.
Check host and port; some networks block 25, so use 587 or 2525.
Messages are accepted but land in spam.
Set up SPF, DKIM and DMARC for your domain as your mail service describes.

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