How to Set Up a Custom SMTP Hostname

A custom SMTP hostname lets you send email through MailerLogic using a hostname on your own domain, such as smtp.yourbrand.com, instead of the shared MailerLogic SMTP host. This is useful for agencies, platforms, and businesses that want a white-labelled SMTP setup.

You can manage custom SMTP hostnames from SMTP → Custom hostnames.

Why Use a Custom SMTP Hostname?

By default, SMTP connections use the shared MailerLogic host:

smtp.mailerlogic.net

With a custom hostname, you can use a hostname on your own domain:

smtp.yourbrand.com

The custom hostname is a CNAME that points to MailerLogic infrastructure and uses its own TLS certificate.

A custom hostname can help you:

• White-label SMTP: Give customers SMTP settings that don't reference MailerLogic.

• Simplify integrations: Your developers and customers can configure your own domain as the SMTP server.

• Maintain a consistent hostname: Applications can continue using a hostname you control.

What a Custom Hostname Does Not Change

A custom SMTP hostname:

• Does not automatically improve deliverability or sending reputation.

• Does not change the From address recipients see.

• Does not provide a dedicated IP address.

Before You Start

Make sure you have:

1. A paid plan that includes custom SMTP hostnames.

2. Access to your domain's DNS settings.

3. An unused subdomain, such as smtp.yourbrand.com or mail.yourbrand.com.

4. A verified sending domain if you want to restrict the hostname to a specific From domain.

You can check whether your plan includes this feature under Usage → Plan features or Billing.

Set Up a Custom SMTP Hostname

Step 1: Add the Hostname

1. Go to SMTP → Custom hostnames.

2. Under Add custom SMTP hostname, enter your hostname, such as smtp.yourbrand.com.

3. Under Sending domain, optionally select a verified domain to restrict the hostname to that domain.

4. Click Add hostname.

Only verified sending domains appear in the Sending domain list.

A dialog displays the DNS record you need to create. Keep this information available while configuring your DNS.

Step 2: Add the CNAME Record

Sign in to your DNS provider and create a CNAME record using the values shown in MailerLogic.

Some DNS providers require only the subdomain portion, such as smtp, in the Name/Host field.

Cloudflare: Set the CNAME record to DNS only using the grey cloud. Do not proxy the record, as proxying can prevent SMTP connections and SSL certificate issuance.

Tip: If your DNS provider automatically adds your domain and creates a value such as smtp.yourbrand.com.yourbrand.com, enter only smtp as the hostname.

Step 3: Verify the DNS Record

DNS changes usually take a few minutes to propagate, although some providers may take up to an hour.

1. Return to SMTP → Custom hostnames.

2. Find your hostname.

3. Click Verify DNS.

4. Wait for the status to change from DNS pending to DNS verified.

If verification fails, wait a few minutes and try again.

Step 4: Request an SSL Certificate

After DNS verification succeeds:

1. Click Request certificate.

2. Wait for the certificate to be issued.

3. Once successful, the status changes from SSL pending to SSL active.

Certificate issuance is automatic and usually takes less than a minute. Your hostname is ready to use once SSL is active.

Step 5: Assign the Hostname to an SMTP Credential

You can associate your custom hostname with an SMTP credential so that the credential uses your branded hostname.

1. Go to the Credentials tab.

2. Open the ⋯ menu for the credential.

3. Select Edit.

4. Set Custom SMTP hostname to your new hostname.

5. Click Save.

Only hostnames with SSL active appear in the dropdown.

Understand Hostname Statuses

Each custom hostname displays status badges that show whether it is ready for use.

Do not use a custom hostname in production until it shows both DNS verified and SSL active.

Connect Your Application

Open Connection details for your hostname to view the SMTP settings.

Port 2525 can be used when port 587 is blocked by your hosting provider or ISP.

Choose a Username

You can authenticate using either your account email address or Customer ID.

Use the Customer ID if the same email address is associated with multiple accounts or if your provider requires a fixed identifier.

Find Your SMTP Password

For security, the Connection details dialog for custom hostnames does not display the password.

To access or change the password:

1. Go to the Credentials tab.

2. Open the credential's ⋯ menu.

3. Select Connection details, or choose Rotate password to generate a new password.

Manage SMTP Credentials

Your SMTP credential provides the authentication details used to connect to MailerLogic. The custom hostname only provides the SMTP address.

Account Credential

Every account has a built-in master credential, shown as Account (master) or Default SMTP (account). You can rotate its password, but you cannot delete or rename it.

Named Credentials

You can create additional credentials by selecting Create credential. Each credential can have:

• A Name

• A Sending domain

• A Custom SMTP hostname

• Optional daily and monthly sending limits

You can also use the ⋯ menu to rotate, disable, enable, or delete named credentials.

For security, use separate credentials for different applications. This allows you to rotate or disable one credential without affecting your other integrations.

Manage Multiple Hostnames

You can create multiple custom hostnames. This can be useful when managing multiple brands or separating production and staging environments.

Each hostname requires its own:

• CNAME record

• DNS verification

• SSL certificate

Each hostname can also be linked to a different credential and sending domain.

Remove a Custom Hostname

Before removing a hostname, make sure no application is still using it.

1. Go to SMTP → Custom hostnames.

2. Click Remove for the hostname.

3. Confirm the removal.

4. Repoint any applications using the hostname to the default SMTP host.

5. Delete the corresponding CNAME record from your DNS provider.

Applications that continue using a removed hostname will fail to send email.

Troubleshooting

DNS Is Not Verified

If DNS verification is still pending:

• Wait 5–15 minutes. Some DNS providers can take up to an hour.

• Check whether the hostname was accidentally duplicated, such as smtp.yourbrand.com.yourbrand.com.

• Confirm that the record type is CNAME, not A or TXT.

• If using Cloudflare, confirm that the record is set to DNS only.

• Check for an existing A or CNAME record that conflicts with the hostname.

SSL Certificate Failed

• Verify that the CNAME is resolving correctly.

• If you recently changed the CNAME, wait for cached DNS information to expire.

• Request the certificate again.

• If the issue continues despite correct DNS configuration, contact support with your hostname.

Connection Is Refused or Times Out

• Try port 2525 if port 587 is blocked.

• Confirm that the hostname shows SSL active.

• Check your server's outbound firewall rules.

Authentication Fails

• Confirm that you're using your SMTP password, not your MailerLogic login password.

• If you recently rotated the password, update every application using that credential.

• Make sure the credential is active.

• Try using your Customer ID instead of your email address as the username.

Email Is Accepted but Not Delivered

This is generally a sending-domain issue rather than a custom hostname issue.

• Verify your From domain under Domains.

• Make sure SPF and DKIM are configured.

• If the credential is restricted to a specific sending domain, make sure your From address uses that domain.

• Check Bounces and Suppressions.

The Custom Hostnames Tab Is Disabled

Your current plan may not include custom SMTP hostnames.

Check Usage → Plan features or upgrade under Billing. Standard SMTP credentials on the Credentials tab continue to work even when custom hostnames are unavailable.

Frequently Asked Questions

Do I need a custom hostname to use SMTP?

No. SMTP works with the default MailerLogic host on any paid plan that includes SMTP. Custom hostnames are intended for white-labelled SMTP connections.

Will a custom hostname improve deliverability?

No, not by itself. Deliverability depends on factors such as your sending domain's SPF, DKIM, and DMARC authentication, list quality, and sending behavior. A custom hostname changes the address your application connects to, not how mailbox providers evaluate your email.

Will recipients see my custom SMTP hostname?

No. Recipients see your From address and sending domain. The SMTP hostname is used by the application making the SMTP connection.

Can I use my root domain as the SMTP hostname?

No. Use a subdomain such as smtp.yourbrand.com or mail.yourbrand.com.

A CNAME on the root domain can interfere with your website and email routing.

How long does setup take?

The setup usually takes less than 15 minutes. DNS propagation can vary by provider, while SSL certificate issuance typically takes less than a minute after DNS verification.

Does the SSL certificate renew automatically?

Yes. The certificate renews automatically as long as the CNAME remains in place. Removing or changing the DNS record can prevent renewal.

Can I use the same hostname across multiple MailerLogic accounts?

No. A custom hostname can resolve to only one MailerLogic account.

Does a custom hostname work with the API?

Custom hostnames apply to SMTP connections. The MailerLogic API is not affected.

Who can manage custom hostnames?

Hostname and credential management is available to account owners and admins.

Related Articles

• Domains: Verify your sending domain with SPF and DKIM.

• Usage → Plan features: Check whether your plan includes custom SMTP hostnames.

• Teams & User Invitations: Learn who can manage SMTP settings.

• Email Builder: Create and design the emails you send.