Email Delivery Best Practices


To ensure the most robust and reliable email delivery, we recommend following these best practices when using Gravity SMTP.

Use a Valid “From” Email Address

Double-check the From Email address you have configured for the active integration. It must be an email address authorized by the integration to be used as the sender. This will usually be an email address using your site domain. If you are in doubt, you will want to refer to the integration documentation or contact their support staff to clarify.

If the email is a Gravity Forms Notification, check the note in the Troubleshooting Notifications documentation.

Configure your SPF and DMARC Records

SPF and DMARC records are designed to allow third-party email servers to validate the authenticity of the email sender. These records are configured in your domain DNS settings and are something you will need to configure in your domain registrar or DNS control panel.

The absence or misconfiguration of these records can cause the email to be marked as spam or be rejected. DMARC records are not required; while they are widely adopted, not every email server uses them. If your integration provides the option to configure a DMARC record, we recommend taking advantage of that.

If you use the Custom SMTP integration to send the emails using your host’s SMTP server and your domain DNS is handled by the same host, you may already have a valid SPF record configured. Contact your hosting support if you are unsure. If you are using a third-party SMTP or API integration, the third-party service will provide you with detailed instructions and support to configure these records. Reach out to your host for additional assistance configuring DNS records.

Below, you will find the documentation for some widely used integrations:

Check the Attachments Policy

Email is an ancient service that predates our beloved Internet. When it was first introduced, it was very common to have an email Inbox of no more than a few thousand Kilobytes. File attachments you may consider small now (e.g., a 20MB photo), weren’t something the creators of the original email standard ever imagined.

Email servers have evolved little regarding email attachments. This is why many current email servers (and email providers) still have a policy that limits the number of attachments per email, the total size of all attachments, the maximum size for each file, and even the file type.

These limitations are applied at the sending server (your active integration), whether using a free or paid service. Even with a paid integration having a generous attachments policy, your emails are still subject to the provider attachment limitations. That means even if your sending integration can handle the attachments, it’s possible the visitor’s email provider (be that Gmail, Yahoo!, Outlook 365, or a corporate email server) may not be able to handle the attachments, and the email will not be delivered.

See below the current limits for some widely used integrations at the time of writing this documentation:

  • Mailgun sets a size limit of 25MB for your email, including attachments. See point 3.2 of their terms page.
  • Postmark sets a 5MB limit for the email body, raised to 10MB if the email contains attachments. See the following support article for more details.
  • SendGrid sets a total size limit of 30MB for your email, including attachments. They recommend that your attachments do not exceed 10MB. For more details, please reach out to SendGrid support.

Avoid Using SMTP Servers from Free Email Accounts

There are several well-known companies providing email accounts for free, which also include support for SMTP usage. The most popular of these is Google’s Gmail. The SMTP servers for these free email accounts weren’t designed to be used for sending emails from a website. They were intended for personal use, such as configuring your email account on your mobile or desktop email client.

For this reason, the providers of free email accounts apply several limitations to their SMTP servers to ensure no misuse of their resources. Experience tells us that some providers document some limitations, and others are applied without warning or notice.

The most common areas of restriction are:

  • Limit the number of emails sent during a specific period of time.
  • Limit the From Address allowed for email messages to the email address your email account uses.
  • Limit the number of recipients you can add per email message.

These are just a few examples. Each provider will apply its own limitations and restrictions. If you want to use one of these free email account SMTP servers for your website email delivery, please contact the provider to clarify their limitations and restrictions.

We don’t recommend using these SMTP servers due to the abovementioned restrictions.

Still Having Trouble?

Please see our Gravity SMTP Troubleshooting Guide.