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SMTP relay without authentication

Open marksmenit opened this issue 6 months ago • 10 comments

Is it possible to disable authentication for custom SMTP relay? The one we used authenticates based on IP address and sender domain, but not username and password.

marksmenit avatar Jun 09 '25 06:06 marksmenit

Can you tell me more detail? And can you show me how do your SMTP authentication working?

dreambladeflag avatar Jun 09 '25 10:06 dreambladeflag

It's a secure email gateway. All it looks at is the source IP address where the email is coming from and the sender domain. It doesn't require any authentication. I tried entering dummy credentials, but the test failed with 503. Currently, entering a username and a password for the relay is mandatory.

marksmenit avatar Jun 09 '25 21:06 marksmenit

Are you currently using an authentication-free method to connect to SMTP service? Is this still integrated on your platform? I'd like to understand what tools/methods you're using to connect to SMTP for email sending.

dreambladeflag avatar Jun 10 '25 02:06 dreambladeflag

I am not sure how else to describe it other than how I did twice already. Here is the documentation of the platform. https://docs.sophos.com/central/customer/help/en-us/ManageYourProducts/EmailSecurity/index.html

Office 365 also allows relaying emails without a username and password (though with limitations). We also have an internal SMTP relay that also doesn't need authentication. I think, sending emails without a username and password is not that exotic/rare.

I also think my original question is rather clear - Is it possible to disable the user authentication for the SMTP relay, which currently is mandatory?

marksmenit avatar Jun 10 '25 05:06 marksmenit

BillionMail currently does not allow connections to your SMTP service without a valid username and password. Thank you for your patience. Actually, this is unusual for me because I’m not used to this setup, so I just needed to confirm.

dreambladeflag avatar Jun 10 '25 06:06 dreambladeflag

We have many clients who have an internal relay that doesn't need authentication.

Any plans to remove this requirement? Needing credentials for SMTP relay. With this, we cannot integrate the system with the others we already have in place and I'm keen to avoid one-off/different setups.

marksmenit avatar Jun 10 '25 06:06 marksmenit

Can you provide a server for us to confirm & fix this issue? This would be very helpful for us.

We are patiently waiting for your email at [email protected].

dreambladeflag avatar Jun 10 '25 06:06 dreambladeflag

We don't have any Internet-facing servers that are open to public.

All we need is that the username and password fields are not mandatory and when not used, the SMTP authentication is skipped.

marksmenit avatar Jun 10 '25 07:06 marksmenit

BillionMail's SMTP relay is based on Postfix and appears unable to bypass authentication for relaying.

dreambladeflag avatar Jun 10 '25 07:06 dreambladeflag

I set up an interim SMTP relay that does require authentication and I get the same error message. The credentials are correct and relay from another computer on the same network works fine. SMTP connection failed: SMTP auth: 503 AUTH command used when not advertised

marksmenit avatar Jun 16 '25 05:06 marksmenit