Why emails are blocked by Gmail and how to resolve?

What is the issue?

Gmail can block and bounce emails when it is sent using programs such as Apps Script or add-ons

Context

When users of Gmail are trying to send email through apps script program or using add-ons like Form Director, Fillable Document etc, Gmail may block or bounce these emails. Read below to see the reason for such blocking and how to resolve it.

When can this happen?

Emails could be blocked for one of the following reasons

  • Google suspects spam/ phishing

  • Too small email

  • Malicious attachment

  • Incorrect Mail Records with Domain Registrar

How to resolve?

One needs to understand the cause of the issue first to resolve the issue. Once the cause is identified, follow the resolution steps below to resolve for good.

Correcting Invalid Mail Contents

If the content is too small or having malicious attachments, ensure that your source program of the email is making good content. For example, .com or .exe files should never be attached in the email.

Correcting Mail records in Domain Registrar

Ensure that your SPF, DKIM and DMARC records with your domain registrar is configured correctly so that email gateways can verify the authenticity of the email

  • SPF

  • DKIM

  • DMARC

If any of these records in your domain registration is incorrect, you need to correct these and then try again. Note that your domain provider might take up to 24 hours to propagate the changes.

Google Workplace Support

Both Gmail service and Apps Script (add-ons are built using Apps Script) are from Google, and hence reach out to Google Workspace support to find why Gmail is blocked. Once you find out the cause, follow the remedial actions above.