Email Servers Overview

Broadcast gives you full control over how your emails are delivered by connecting to the email service provider (ESP) of your choice. Rather than routing messages through a single, opaque sending system, Broadcast lets you plug in your own provider credentials so you control deliverability, costs, and sender reputation from day one.

Why You Need an Email Server

Broadcast is your command center for composing, scheduling, and managing email campaigns – but it doesn’t send emails directly. Instead, it connects to one or more external email providers to handle the actual delivery. This approach gives you several advantages:

• Choose the provider that fits your budget and volume – from low-cost options like Amazon SES to premium transactional providers like Postmark
• Maintain your own sender reputation – your domain, your IP reputation, your deliverability
• Switch providers without rebuilding your campaigns – swap credentials and keep sending
• Scale with multiple providers – distribute load across servers for higher throughput

Supported Providers

Broadcast works with a wide range of email service providers out of the box:

The Test Server is pre-configured on your account and lets you send emails to yourself for testing purposes. It is perfect for previewing broadcasts and verifying your workflow before connecting a production provider.

Delivery Methods: SMTP vs API

When adding an email server, you choose how Broadcast communicates with your provider.

SMTP (Simple Mail Transfer Protocol)

SMTP is the traditional, universal method for sending email. Every provider supports it, and it works the same way everywhere:

• Universal compatibility – works with any email provider
• Well-understood protocol – decades of reliability
• Straightforward configuration – address, port, username, password

API Delivery

For supported providers (currently AWS SES and Postmark), Broadcast can send emails directly through the provider’s API instead of SMTP:

• Faster delivery – eliminates the SMTP handshake overhead
• Better error reporting – structured error responses instead of cryptic SMTP codes
• Provider-specific features – take advantage of native capabilities like SES configuration sets or Postmark message streams

If your provider supports API delivery, it is generally the recommended option for better performance and richer feedback.

Adding an Email Server

To connect a new email provider:

1. Go to Settings > Email Servers in your dashboard
2. Click Add Email Server – a slide-over panel opens
3. Fill in the configuration fields

Basic Configuration

• Label – a friendly name to identify this server (e.g., “Production SES” or “Transactional - Postmark”)
• Vendor – select your email provider from the dropdown
• Delivery Method – choose SMTP or API (when available for the selected vendor)

SMTP Configuration

When using SMTP delivery, you will need to provide:

• SMTP Address – your provider’s SMTP endpoint (e.g., email-smtp.us-east-1.amazonaws.com)
• Port – typically 587 (STARTTLS), 465 (SSL/TLS), or 25 (unencrypted, not recommended)
• Username – your SMTP username or API key
• Password – your SMTP password or secret key
• Authentication Type – choose from Plain, Login, or CRAM-MD5 depending on your provider’s requirements

API Configuration

For API-based delivery, the fields vary by provider:

• AWS SES – Access Key ID, Secret Access Key, AWS Region (e.g., us-east-1), and optionally a Configuration Set name for tracking
• Postmark – Server API Token (found in your Postmark server settings)

Testing Your Connection

After entering your credentials, click the Test Connection button to verify everything is configured correctly. Broadcast will attempt to authenticate with your provider and report any issues. Always test before saving to catch typos or permission problems early.

Advanced Settings

Each email server has several optional settings that give you finer control over delivery behavior.

Custom Headers

Add custom email headers to messages sent through this server. This is useful for:

• Tracking metadata your provider uses for analytics
• Adding custom identifiers for internal routing
• Provider-specific headers that enable advanced features

Email Types

Assign each server to handle specific types of email:

• Broadcasts – bulk campaigns sent to your subscriber list
• Transactional – one-to-one messages triggered by actions (password resets, confirmations)
• Sequences – automated drip campaign emails

Separating email types across different servers is a deliverability best practice. Transactional emails need high inbox placement, and mixing them with bulk broadcasts on the same server can hurt their reputation. By dedicating a server to each type, you keep your sending reputation clean and your deliverability high.

Custom Unsubscribe Settings

Fine-tune unsubscribe behavior on a per-server basis:

• Include Unsubscribe Header – adds the List-Unsubscribe and List-Unsubscribe-Post headers that Gmail, Yahoo, and other mailbox providers require for one-click unsubscribe
• Include Unsubscribe Link – controls whether an unsubscribe link appears in the email footer
• Custom Unsubscribe Link – for providers like Postmark that inject their own unsubscribe mechanism, you can specify a custom variable (e.g., {{{ pm:unsubscribe }}}) instead of the default Broadcast link

Enable / Disable Server

You can temporarily disable an email server without deleting it. This is helpful during maintenance windows, when troubleshooting delivery issues, or when rotating provider credentials. Disabled servers retain all their configuration so you can re-enable them instantly.

Rate Limiting

Broadcast displays the current rate limit for each email server so you can understand your sending capacity at a glance. Rate limits are typically set by your email provider (for example, SES sandbox accounts start at 1 email per second). Broadcast respects these limits automatically and queues messages accordingly.

Load Balancing Across Multiple Servers

One of Broadcast’s most powerful features is the ability to connect multiple email servers and automatically distribute your sending load. When you have more than one active server configured for the same email type, Broadcast balances delivery across them. This gives you:

• Higher throughput – combine the rate limits of multiple providers
• Redundancy – if one provider goes down, your other servers keep delivering
• Cost optimization – mix providers based on pricing tiers

Email Server Status Display

The Email Servers settings page gives you a clear overview of each configured server:

• Server name and vendor – quickly identify each connection
• Connection details – SMTP address or API endpoint
• Rate limits – current sending speed allowance
• Email type badges – visual indicators showing which types (Broadcast, Transactional, Sequence) each server handles

Best Practices

• Always test your connection before saving a new server – catching credential issues early saves debugging time later
• Monitor delivery metrics after connecting a new provider – watch for bounces, complaints, and delivery rates in the first few sends
• Separate servers by email type – use dedicated servers for broadcasts, transactional emails, and sequences to protect deliverability
• Respect rate limits – if you are hitting your provider’s limits, add a second server rather than trying to override the cap
• Keep a backup server – configure a secondary provider so you have a fallback if your primary goes offline
• Use API delivery when available – for AWS SES and Postmark, API delivery offers faster sending and better error feedback

Next: ESP Integrations – Set up webhooks to track deliveries, bounces, and engagement events from your email provider.