How to Connect a Custom SMTP Service in Sparkforge

By Sparkforge Support Team ·Last reviewed May 3, 2026

You can route outbound email through your own SMTP provider — Gmail, SendGrid, Mailgun, Amazon SES, Postmark, Yahoo, or Zoho — instead of the default Sparkforge Email System. Some built-in deliverability tools turn off when you do.

You can connect a third-party SMTP service to your Sparkforge sub-account instead of using the default Sparkforge Email System. This is useful when you already have an established sending reputation, need higher volume, or want to manage your own infrastructure.

Where to find Email Services

  1. Log in to your sub-account.
  2. Click Settings in the left sidebar.
  3. Select Email Services.
  4. Open the SMTP Service tab (some interfaces label it Advanced Settings — same screen).

Default vs. custom SMTP

Sparkforge Email System (default)Custom SMTP (third-party)
Managed by Sparkforge.Managed by you or your provider.
Full access to built-in deliverability tools.Several built-in tools become unavailable.
No extra setup.Requires SMTP credentials from your provider.
Recommended for most users.Best for users with existing sending infrastructure.

Supported SMTP providers

When you click + Add Service, you can choose:

  • Gmail (Google Workspace or personal)
  • Yahoo Mail
  • SendGrid
  • Other (Mailgun, Amazon SES, Postmark, Zoho, or any SMTP-compatible service)

Add a custom SMTP service

  1. Open Email Services. Settings → Email Services → SMTP Service.
  2. Click + Add Service. A popup titled Add your own email service appears.
  3. Select your provider from the SMTP Provider dropdown.
  4. Enter SMTP credentials from your provider:
    • SMTP Host — outgoing mail server (for example, smtp.sendgrid.net)
    • Port — 587 (TLS) or 465 (SSL)
    • Username — SMTP login or API key identifier
    • Password / API Key — from your provider
    • From Name — the display name recipients see
    • From Email — the sender address
  5. Save and set as active. Find the new service in the list, click Set as active, and confirm.

You can save multiple SMTP services and switch between them, but only one is active at a time.

Common SMTP settings reference

ProviderSMTP HostPortNotes
Gmailsmtp.gmail.com587 / 465App Password required if 2FA is on.
SendGridsmtp.sendgrid.net587Use apikey as the username.
Mailgunsmtp.mailgun.org587Use Mailgun SMTP credentials.
Amazon SESemail-smtp.[region].amazonaws.com587Requires IAM SMTP credentials.
Postmarksmtp.postmarkapp.com587Use the server API token.
Yahoo Mailsmtp.mail.yahoo.com587App password required.
Zoho Mailsmtp.zoho.com587Use your Zoho account credentials.

Limitations of third-party SMTP

Switching off the default Sparkforge Email System turns off these features:

  • Creating a dedicated sending domain from inside the app
  • Google Postmaster Tools integration
  • Microsoft Postmaster Tools integration
  • Risk Assessment
  • Bounce Classification
  • Inbox Placement Testing
  • Spam Score Checker
  • Blacklist Monitor
  • Managed Domains and IPs

If those tools matter to your sending strategy, stay on the Sparkforge Email System.

Enable reply for SMTP

On the active SMTP service, check Enable reply to route inbound replies into Sparkforge conversations. Without it, replies land in your provider’s inbox and never reach the CRM.

Switch back to Sparkforge

  1. Go to Settings → Email Services → SMTP Service.
  2. Click Sparkforge Email System.
  3. Click Set as active.

Saved SMTP services stay in the list and can be reactivated later.

Frequently Asked Questions

Can I save more than one SMTP service?
Yes. You can save multiple, but only one can be active for outgoing email at a time.
Will my contacts see the SMTP provider details?
No. Recipients only see the From Name and From Email you configure.
What happens to emails already sent if I switch providers?
Switching only affects future sends. Previously sent messages are not changed.
My SMTP connection is failing — what should I check?
Verify host, port, username, and password. Confirm port 587 or 465 is not blocked. Use an App Password for Gmail with 2FA. Verify your SendGrid sending domain. Confirm the From address is authorized in your provider.
Should I use port 587 or 465?
Use 587 with TLS for most modern providers. Use 465 with SSL if 587 is blocked on your network.
Will replies route into Sparkforge?
Only when Enable reply is checked on the active SMTP service. Then inbound replies are tracked in conversations.

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