Response codesEach SMTP call you make returns a response. Show
Turning off click trackingTo turn off click tracking, add this to your X-SMTPAPI header:
Invalid SMTP API headerWhen you try to send an invalid X-SMTPAPI header, you will get an email with details about the invalidations. You may also see errors on your Email Activity page or in your Event Webhook data. If this happens, the email should give you the information you need to begin troubleshooting. We also recommend uploading your JSON into a JSON validator, because this is often an invalid JSON issue. Certificate verification failed for smtp.sendgrid.net
If you receive this error, the connection is still encrypted; it's just that your server doesn't have the necessary CA (certificate authority) certificates to confirm that our certificate is valid. To update your certificates:
If the mail server communicates with more than just
us, add this certificate to your existing CA bundle (frequently called 550 Unauthenticated Senders Not AllowedIf you’re getting an “Unauthenticated Senders Not Allowed” error, the problem usually lies in authenticating with our SMTP server. This error gets triggered when there was an attempt to hand over an email message through smtp.sendgrid.net before authenticating the connection with your SendGrid username and API key. To fix this issue, you’ll want to make sure that you’ve configured your setup to connect to If you’re using cPanel/Exim, you’ll want to make sure it’s configured to authenticate every time it connects to Additional Resources |