ESP integrations

EmailBuilder doesn't deliver mail itself — it composes the template, then hands it off to an Email Service Provider (ESP) you've connected. This page covers connecting an ESP, what each provider supports, and quirks to watch for.

Supported providers

Provider	Contact lists	Segments	CSV sends	Notes
Mailchimp	✓	✓ (per list)	✓	Segments are scoped to a single list.
SendGrid	✓	✓	✓	Has suppression groups; surface them on the connection page.
Mailgun	✓	—	✓	Mailing lists only; no native segments.
Brevo (Sendinblue)	✓	✓	✓
Postmark	✓	—	✓	CSV sends require choosing a message stream.
Mailjet	✓	✓	✓
HubSpot	✓	✓	—	Marketing Hub Professional+ required for sending.
AWS SES	✓ (native lists)	—	✓	Bounces are tracked. Configure SES verified identities + DKIM in your AWS account before connecting.
Gmail / Outlook	n/a	n/a	n/a (direct only)	OAuth-based. Use for one-to-one. See Gmail add-on.

Connecting a provider

1. Go to Account → Integrations.
2. Click Connect next to the provider you want.
3. Paste the credentials the provider requires:
   • API key for most providers.
   • OAuth flow for Gmail and Outlook — you'll be redirected to sign in.
   • AWS access key + secret + region for SES.
4. Click Save. EmailBuilder makes a probe request to verify the credentials work.

A green dot on the connection means it's healthy. A red dot means the last probe failed — click into the connection for the error message (usually expired credentials or insufficient permissions).

What the connection unlocks

Each healthy connection unlocks:

• Send Wizard — when creating a send from a template, this provider appears in the From dropdown.
• List & segment picking — the wizard fetches lists and segments from the provider on demand.
• Contact management — a Contacts page that proxies CRUD to the provider's API (lists, members, segments). For AWS SES, contacts are stored natively in SES.
• Stats — sent count, opens, clicks, bounces, complaints surface on the Send detail page after delivery.

Some features depend on what the provider supports. The Send Wizard adapts: if you connect Mailgun (no segments), the Segments option is hidden. If you connect Postmark, a Message Stream picker appears for CSV sends.

Provider-specific setup

Mailchimp

• Use an API key from the Mailchimp account ("Account → Extras → API keys").
• The connection picks up the data center from the key suffix (-us21, etc.) automatically.
• Segments are scoped to a list: when picking a segment in the wizard, pick the parent list first.

SendGrid

• Use a Full Access API key (or a custom one with Mail Send + Marketing scopes).
• Optionally pick a suppression group on the connection — sends will associate with that group so unsubscribes flow into it.
• The connection page surfaces your existing suppression groups; create new ones in SendGrid directly.

Postmark

• Use a Server API token (one per server in Postmark).
• For CSV / direct sends, pick a message stream in the wizard. Postmark requires one — transactional and broadcast streams are separate billing.

AWS SES

• Set up a verified identity (domain or address) in SES before connecting.
• Enable DKIM on the verified identity. SES will provide three CNAME records; add them to your DNS.
• Create an IAM user with AmazonSESFullAccess (or a tighter custom policy) and use its access key + secret.
• Pick the region of your SES configuration when connecting.
• For bounce handling, EmailBuilder receives SNS notifications when you configure a topic — see Deliverability.

Mailgun

• Use a Sending API key (per domain).
• Pick the API region (US or EU) — different domains.

HubSpot

• OAuth flow. You'll be redirected to HubSpot to grant marketing-email scopes.
• Requires Marketing Hub Professional or Enterprise to send.

Connecting multiple providers

You can connect more than one provider per account — useful for separating transactional and marketing traffic, or for running multi-domain sends from different identities. Each send in the wizard picks one provider; there's no automatic failover between them.

Disconnecting

Account → Integrations → click a provider → Disconnect. The connection is removed and any future sends through it will fail until reconnected. Sends already scheduled with that connection won't auto-reroute — cancel and re-create them if needed.