How to Add Your Own Email Service (SMTP)

Email InfrastructureSetting Up a Custom SMTP ServiceConnect your own third-party email sending service, Gmail, SendGrid, Mailgun, Amazon SES, and more, directly inside your sub-account.Overview

The platform allows you to connect your own third-party email sending service (SMTP) instead of using the default Open Doors Email System. This is useful if you already have an established sending reputation, need higher volume limits, or prefer to manage your own email infrastructure.

This guide walks you through adding, configuring, and activating a custom SMTP service inside your sub-account.

Table of Contents1Where to Find Email Services2Default vs. Custom Email Service3Supported SMTP Providers4Step-by-Step: Adding a Custom SMTP Service5Common SMTP Settings Reference6Important: Limitations of Third-Party SMTP7Enable Reply for SMTP8Switching Back to Open Doors9Frequently Asked QuestionsVideo Walkthrough1

Where to Find Email Services

Navigate to the Email Services settings using the steps below:

1. Log in to your sub-account
2. Click Settings in the left sidebar
3. Select Email Services
4. Go to the SMTP Service tab (or Advanced Settings depending on your interface version)

Tip

Your interface may show tabs labeled 'SMTP Service' or 'Advanced Settings', both lead to the same SMTP configuration area.

2

Default vs. Custom Email Service

A side-by-side comparison to help you decide which option fits your business:

Open Doors (Default)	Custom SMTP (Third-Party)
Managed by the platform	Managed by you / your provider
Full access to all built-in deliverability tools	Some built-in tools are unavailable (see limitations)
No extra setup required	Requires SMTP credentials from your provider
Recommended for most users	Best for users with existing sending infrastructure

3

Supported SMTP Providers

When you click + Add Service, you can choose from the following providers:

Gmail, Google Workspace or personal GmailYahoo MailSendGridOther, covers Mailgun, Amazon SES, Postmark, Zoho, and any SMTP-compatible serviceSetup GuideAdding a Custom SMTP ServiceFollow these five steps to connect your third-party email service.4

Step-by-Step: Adding a Custom SMTP Service

Step 1Open Email Services

Go to Settings → Email Services → SMTP Service tab.

Step 2Click + Add Service

In the top-right corner of the page, click the + Add Service button. A popup will appear titled 'Add your own email service'.

Step 3Select Your SMTP Provider

From the SMTP Provider dropdown, select your provider:

• Gmail
• Yahoo Mail
• SendGrid
• Other (for Mailgun, Amazon SES, Postmark, etc.)

Step 4Enter Your SMTP Credentials

Fill in the required fields. These details come from your email provider's dashboard:

Field	Description
SMTP Host	The outgoing mail server address (e.g., smtp.sendgrid.net)
Port	Usually 587 (TLS) or 465 (SSL)
Username	Your SMTP login username or API key identifier
Password / API Key	Your SMTP password or API key from the provider
From Name	The display name that recipients will see
From Email	The email address emails will be sent from

Step 5Save and Set as Active

Once saved, your new SMTP service will appear in the provider list. To start using it:

1. Find your newly added service in the list
2. Click Set as active
3. Confirm the selection

Tip

You can have multiple SMTP services saved and switch between them at any time. Only one can be active at a time.

5

Common SMTP Settings Reference

Quick reference for popular providers, verify values in your provider's dashboard before pasting.

Provider	SMTP Host	Port	Notes
Gmail	smtp.gmail.com	587 / 465	Requires App Password if 2FA is on
SendGrid	smtp.sendgrid.net	587	Use 'apikey' as username
Mailgun	smtp.mailgun.org	587	Use your Mailgun SMTP credentials
Amazon SES	email-smtp.[region].amazonaws.com	587	Requires IAM SMTP credentials
Postmark	smtp.postmarkapp.com	587	Use server API token as credentials
Yahoo Mail	smtp.mail.yahoo.com	587	Requires app password
Zoho Mail	smtp.zoho.com	587	Use your Zoho account credentials

6

Important: Limitations of Third-Party SMTP

When you use a custom SMTP service instead of Open Doors, some platform features become unavailable. Please review these limitations before switching:

Features NOT available with third-party SMTP

• Create dedicated sending domain from the app
• Google Postmaster tools integration
• Microsoft Postmaster tools integration
• Risk Assessment
• Bounce Classification
• Inbox Placement Testing
• Spam Score Checker
• Blacklist Monitor
• Managed Domains & IPs

Important

If these features are important to your email strategy, consider staying on the Open Doors Email System, which gives you full access to all built-in deliverability tools.

7

Enable Reply for SMTP

When viewing your active SMTP service, you will see an Enable reply checkbox. Enabling this allows inbound replies to emails sent through your SMTP to be received and tracked inside platform conversations.

Tip

If you need two-way email communication with your contacts, make sure Enable reply is checked for your active SMTP service.

8

Switching Back to Open Doors

You can switch back to the default Open Doors Email System at any time:

1. Go to Settings → Email Services → SMTP Service
2. Click on Open Doors Email System
3. Click Set as active (or select it as the default)

Good to Know

All your custom SMTP services will remain saved and can be reactivated later.

9

Frequently Asked Questions

Q: Can I have multiple SMTP services saved?Yes. You can save as many SMTP services as you like. However, only one can be active at a time for outgoing emails.Q: Will my contacts see the SMTP provider details?No. Contacts only see the From Name and From Email you configure, not the underlying SMTP provider details.Q: What happens to emails already sent if I switch providers?Switching providers only affects future emails. Previously sent emails are not affected.Q: My SMTP connection is failing, what should I check?

• Verify that the SMTP host, port, username, and password are correct
• Make sure port 587 or 465 is not blocked by your email provider
• For Gmail, ensure you are using an App Password (not your regular login password) if 2-Step Verification is enabled
• For SendGrid, ensure your sending domain is verified in your SendGrid account
• Check that your sending email address is authorized within your SMTP provider's account

Q: Does using custom SMTP affect my built-in email deliverability tools?Yes. Several built-in deliverability tools (Postmaster integrations, Risk Assessment, Bounce Classification, Inbox Placement, Spam Score Checker, Blacklist Monitor, and Managed Domains/IPs) become unavailable when you switch to a third-party SMTP. Refer to the limitations section above.Q: Which SMTP port should I use, 587 or 465?Use 587 with TLS (recommended by most modern providers) and 465 with SSL. If one port is blocked by your network, try the other.Q: Will replies to my emails come back into the platform?Only if you check the Enable reply option on your active SMTP service. With this enabled, inbound replies are received and tracked inside platform conversations.