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Missing notifications for read email messages

Sometimes, you might not receive message.opened webhook notifications when a recipient has read an email message.

Nylas detects that an email message has been read by embedding a single-pixel image file in the message HTML and tracking when that image is downloaded. Nylas tracks the initial download only.

Nylas might not generate message.opened webhook notifications for any of the following reasons:

  • The email client reads text-based email messages only, and doesn't accept HTML. This means the single-pixel image file is never downloaded.
  • The email client strips attachments and replaces them with literal HTML that represents the file name (for example, <spacer.gif> might be appended to the message).
  • The email client strips image files from HTML email messages.
  • The email client doesn't allow image files to be downloaded.


In this case, you must contact the recipient and verify that their email client allows them to receive images in email messages.

As a work-around, you can also combine Message Open tracking with Link Clicked tracking to determine that email messages have been opened after recipients click an embedded link.


For more information about message tracking and the webhooks Nylas generates, see the following documentation: