How to Send Email From Your Custom Domain Using Gmail's "Send As"

By Forward Team Apr 25, 2026 9 min read Tutorials

You have your domain, and you're receiving emails thanks to forwarding. But how do you reply? Here is the definitive guide to sending professional emails from your custom domain using your existing Gmail inbox.

This is the outbound half of the workflow. If inbound forwarding is not already working, fix that first.

Email forwarding is brilliant for consolidating multiple addresses into one inbox. But the illusion breaks instantly if you reply to a business inquiry and it comes from yourname89@gmail.com instead of hello@yourstartup.com.

To fix this, you need to configure Gmail to send emails as your custom domain. And to do that reliably, you need dedicated SMTP credentials.

Why Not Just Use Gmail's Default SMTP?

Historically, Gmail allowed users to send emails from an alias using Google's own SMTP servers for free. You still can, but there are massive downsides:

  • Deliverability Drops: Modern spam filters (including Google's own) look closely at sender alignment. If the email claims to be from yourdomain.com but the underlying envelope says it was sent via free consumer Gmail, it's highly likely to be flagged as spam or given a generic "via gmail.com" warning.
  • Reputation Risk: Using a shared, free SMTP server means your domain's reputation is tied to whatever everyone else on that server is doing.
  • Security: Relying on less secure app passwords or generic app integrations opens up unnecessary security risks for your personal inbox.

The Solution: Use Forward's dedicated SMTP infrastructure. By routing your outbound mail through the same system that handles your inbound mail, your SPF, DKIM, and DMARC alignment stays pristine, ensuring your emails actually reach the inbox.

Before You Start

  • Your domain must already be verified in Forward.
  • Your inbound forwarding should be live.
  • You need a Gmail account you control.
  • You should know which exact aliases can send mail.

Step 1: Generate an SMTP Credential in Forward

Forward (on the Creator plan or higher) provides purpose-built, highly secure SMTP credentials specifically for this exact workflow.

  1. Log in to your Forward Dashboard.
  2. Navigate to the SMTP section.
  3. Under "Generate a send-as password", select your verified domain.
  4. Crucial Step: Scope your senders. In the "Allowed from addresses" field, type the exact email addresses you plan to send from (e.g., hello@yourdomain.com). This is a massive security feature. If this password ever leaks, attackers cannot use it to send spam from other addresses on your domain.
  5. Click Create SMTP credential.
  6. Copy the generated Username and Password immediately. (You won't be able to see the password again).

Step 2: Configure Gmail's "Send mail as"

Now we plug those credentials into Gmail so it knows how to securely hand off your outbound emails to Forward.

  1. Open your personal Gmail inbox.
  2. Click the gear icon in the top right and select See all settings.
  3. Navigate to the Accounts and Import tab.
  4. In the "Send mail as" section, click Add another email address.
  5. A yellow window will pop up. Enter the Name you want recipients to see (e.g., "Jane from Acme Corp").
  6. Enter your custom domain Email address (e.g., hello@yourdomain.com). Keep "Treat as an alias" checked. Click Next Step.
  7. Now enter your Forward SMTP details:
    • SMTP Server: forward.redsols.com
    • Port: 587
    • Username: The username you copied from Forward (looks like smtp_xxxxxxxxxxxx).
    • Password: The long, secure password you copied.
    • Ensure Secured connection using TLS (recommended) is selected.
  8. Click Add Account.

Gmail will now send a verification code to your custom address. Since you already have Forward routing inbound emails to your Gmail, that code will land in your inbox in seconds. Copy the code, paste it into the yellow window, and click Verify.

Step 3: Test Your Setup

You're fully configured! Let's make sure it works seamlessly.

  1. In Gmail, click Compose.
  2. Click on the "From" field. You should now see a dropdown menu letting you select your custom domain address.
  3. Send a test email to a friend or an alternative email address you own.
  4. Check the receiving inbox. The email should arrive quickly, looking highly professional, with no "via gmail.com" warnings.

Pro Tip: Go back to your Gmail Settings → Accounts and Import. Under "When replying to a message," select Reply from the same address the message was sent to. This prevents you from accidentally replying to a business email with your personal Gmail address.

Common Failure Modes

  • If the alias does not show up in Gmail, the SMTP credential is probably not scoped to that sender.
  • If verification never arrives, inbound forwarding is broken or delayed.
  • If mail lands in spam, re-check the DNS records for the domain you send from.

Understanding Sending Limits

Forward's SMTP service is designed for human sending and transactional emails—not bulk marketing blasts. To protect the reputation of the IPs handling your mail, strict limits are enforced per credential:

  • 10 recipients per minute
  • 100 recipients per hour
  • 500 recipients per day
  • A hard cap of 25 recipients per single message.

If you try to CC 50 people on a single email, or send 1,000 marketing emails at once, the server will gracefully reject the transaction to protect your domain's deliverability. If you need to send bulk newsletters, you should use a dedicated marketing tool like Mailchimp or ConvertKit. But for day-to-day business communication, investor updates, and customer support replies, this setup is flawless.

Ready to look professional?

Get your custom domain email running in minutes. Secure SMTP sending available on Creator and higher plans.

View Pricing