Not Receiving OTP Emails – travel.world Domain Blacklisted in Auth0 Default Email Provider

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Hi Auth0 Community,

I’m currently using the default Auth0 email provider (SendGrid) for authentication emails, but I am not receiving OTP emails when using an email with the domain travel.world.

I checked the domain status using an online blacklist checker and found that travel.world is blacklisted on at least one blacklist. I suspect this might be the reason why emails from Auth0’s email provider are not reaching my inbox.

I have tried the following troubleshooting steps:
:white_check_mark: Checked Auth0 Logs (no email failures shown).
:white_check_mark: Checked spam/junk folders (no emails found).
:white_check_mark: Verified that other domains like Gmail receive OTP emails successfully.
:white_check_mark: Used an online tool (MXToolbox) and confirmed that travel.world is blacklisted.

I don’t have a custom email provider configured in Auth0 yet, and I’m wondering:

  1. Does the default Auth0 email provider (SendGrid) block or filter emails based on blacklisted domains?
  2. Is there any workaround to receive OTPs on my travel.world email?
  3. Would switching to a custom email provider (e.g., AWS SES, Postmark, or SendGrid) help resolve this issue?

Any guidance or suggestions would be greatly appreciated! :rocket:

Thanks in advance.

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Hi @farid1

Thanks for posting your question on the Auth0 Community!

I would like to first clarify that SendGrid is not the default email provider, the default one used is a custom one.

Indeed, the issue might be due to the fact that the domain appears to be blacklisted or flagged and that is why the email are not being received. As an alternative, you can go to Passwordless → Email → Configure → Settings and change the From email address to something else.

The FROM email address does not need to be a valid one, it can be a made up address and you can try again to send a code to travel.world emails. Otherwise, if this also fails, the company domain might be blocking the OTP emails by default since you mentioned that emails such as Gmail receive the codes normally.

As mentioned, when configuring Passwordless, the default Auth0 Email Provider is intended only for development and I would advise to configure a custom email provider for your application.

If you configure a custom email provider, if the travel.world domain would also block the OTPs from the custom email providers, that means the domain admin needs to whitelist the OTP emails.

If you have any other questions, feel free to leave a reply!

Kind Regards,
Nik

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