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How to Connect an Email Provider

The provider is the company that actually relays your email to the inbox providers: SendGrid, Mailgun, Amazon SES, and their competitors. Email Campaign Engine, the free open source engine behind our Email Broadcast app, sends through plain SMTP with its own built-in mail client, so it works with 11 providers out of the box and with any standard SMTP relay besides. This guide walks through opening the account, setting up authentication, and wiring the provider into the engine, and it applies equally to the hosted version.

Step 1: Choose a Provider

Any of the 11 works, so choose on price and fit. Supported with full webhook parsing: SendGrid, Mailgun, Postmark, Amazon SES, SMTP2GO, Brevo, SparkPost, Elastic Email, Mailtrap, Mailjet, and SMTP.com. Anything else with an SMTP relay works for sending, you just will not get its event webhooks.

Amazon SES is the cheapest at volume, around $0.10 per thousand emails, with minimal hand holding. SendGrid and Mailgun cost more but bring better tooling and reputation management. Postmark is superb for transactional mail and strict about bulk marketing. Our guide on choosing an email provider compares them in detail.

Because the engine talks standard SMTP, the provider is swappable. Your contacts, messages, series, and history all stay put if you change providers later, you just update the SMTP settings on the sending domain.

Step 2: Verify Your Domain and Set Up Authentication

This step decides your deliverability. In the provider dashboard, verify your sending domain and publish the DNS records they give you: SPF, DKIM, and DMARC. Every provider walks you through it, and none of your mail reliably reaches Gmail or Yahoo without it.

Use a subdomain for bulk sending, like mail.yourbrand.com, so your marketing reputation stays separate from your day-to-day business email. If the domain is new, plan on warming it: small volumes to engaged contacts first, growing week over week. The setup guides for SPF, DKIM, and DMARC cover each record.

Step 3: Add the Sending Domain to the Engine

Admin area, sending domains, add. Enter the domain, the from alias (the from address becomes alias@domain), and the provider's SMTP host, username, and password. Use port 465 for SSL or 587 for STARTTLS, both work.

Provider	SMTP host	Username	Password
SendGrid	`smtp.sendgrid.net`	apikey	your SendGrid API key
Mailgun	`smtp.mailgun.org`	postmaster@your-domain	Mailgun SMTP password
Postmark	`smtp.postmarkapp.com`	server token	server token
Amazon SES	`email-smtp.us-east-1.amazonaws.com` (region specific)	SES SMTP username	SES SMTP password
SMTP2GO	`mail.smtp2go.com`	SMTP2GO username	SMTP2GO password
Brevo	`smtp-relay.brevo.com`	account email	Brevo SMTP key
SparkPost	`smtp.sparkpostmail.com`	SMTP_Injection	SparkPost API key
Elastic Email	`smtp.elasticemail.com`	account email	Elastic Email API key
Mailtrap	`live.smtp.mailtrap.io`	api	Mailtrap sending token
Mailjet	`in-v3.mailjet.com`	Mailjet API key	Mailjet secret key
SMTP.com	`send.smtp.com`	account username	SMTP.com password

Step 4: Send a Test Email

One click in the dashboard. The admin area has a built-in SMTP test, send yourself a message and confirm it arrives in the inbox, not the spam folder. If it bounces, the SMTP credentials are wrong. If it lands in spam, your authentication records need attention before anything else.

Step 5: Point the Webhooks

Close the feedback loop. In the provider dashboard, point the event webhooks at https://yourdomain.com/webhook.php/{provider}?key=YOURWEBHOOKKEY, with {provider} being the lowercase name, like sendgrid or mailgun. For Amazon SES, subscribe that URL to your SNS topic and the engine confirms the subscription automatically.

The webhooks are how delivered, bounces, opens, clicks, complaints, and unsubscribes flow back into your contact profiles, and how hard bounces and complaints get suppressed automatically. Without them the engine sends fine but learns nothing. The exact event lists per provider are in the documentation, and what the engine does with each event is covered in bounces, complaints, and unsubscribes.

Keep transactional and marketing separate. If you also send receipts and password resets, consider a second sending domain or a stricter provider like Postmark for that traffic. One bad marketing campaign should never be able to take your order confirmations down with it.

Email Campaign Engine is free and open source, and works with every provider above over plain SMTP.

Get the Code on GitHub

Prefer it managed? Contact our team about the hosted Email Broadcast app.