2FA NOW REQUIRED: Twilio is requiring two-factor authentication (2FA) as an additional layer of protection for all paying Twilio customers. For more details, see our 2FA Setup Guide.

Unable to Send Email to Gmail

Users may run into issues when attempting to send email to addresses on the Gmail domain. This can often be due to email appearing outside of the default "Primary" tab, or due to email filtering. This guide covers some information and best practices to help improve your deliverability rate to Gmail.

Gmail's tab system

By default, Gmail user inboxes are displayed in up to 5 tabs for each message segment - Primary, Social, Promotions, Updates, and Forums. A user who does not have tabs enabled will see a single inbox for all incoming messages.

Messages sent to multiple recipients, especially those that include special offers or time-sensitive deals, are likely to end up in the Promotions tab. Emails that end up here are not being filtered like a spam message, but it is assigned to a different section of the recipient's inbox. This is what the Promotions tab was designed for, but ultimately your recipients control which messages end up in that tab versus their Primary tab.

Email shows "Delivered" status

SendGrid posts the Delivered event after the recipient server accepts the message, and sends back to us an HTTP 250 OK response. This is basically server language for the message that has been accepted by the receiving server and from that point on, it is 100% in their control. If a Delivered message does not end up in the recipient's message inbox, it could be that it is being quarantined for some reason, or that the mailbox provider is applying other actions like additional filtering. In this situation, we can only see that the message was successfully delivered to the host - we are unable to see what they do between then and delivery to the recipient.

Please note that each recipient server has slightly different filtering systems. Once the mail leaves SendGrid's servers, we only receive information on if it was "Delivered" or "Blocked" by the recipient server. Once "Delivered," the recipient server determines whether they'd like to filter your mail into an inbox or another folder. Typically, recipient mail servers look at your IP traffic, reputation, and content, as well as engagement, list quality, and spam reports. Gmail is looking with priority at the domain reputation and content.

For more information about your domain's reputation we recommend the following sources:

  • Check your domain's reputation with SenderScore or Talos.
  • Test and rate your messages at MailTester, and follow the suggested improvements.

Additional resources

Have more questions? Submit a request