Need Help: Authentication Failure when Sending Emails via Yunohost Mail Server

Hardware: AMD64
YunoHost version: (stable)
I have access to my server : Yes
Are you in a special context or did you perform some particular tweaking on your YunoHost instance ? : Yes - it’s behind a openVPN Server


Hey Yunohost community,

I’ve been encountering an issue with my Yunohost mail server, and I’m hoping someone here might be able to help me troubleshoot it.

Problem Description:

When attempting to send emails through my Yunohost mail server, I’m receiving an authentication failure error message. The error specifically states: “Sender address rejected: (21) Authentication failed. No client certificate was sent.”

What I’ve Tried:

I’ve already gone through a few troubleshooting steps on my own, including:

  • Verifying the SMTP settings in my email client/server.
  • Checking the authentication credentials to ensure they are correct.
  • Reviewing the certificate settings on my Yunohost server.
  • Ensuring that the sender address being used is authorized by my email provider.

Despite these efforts, I’m still unable to send emails successfully, and the authentication failure persists.

Seeking Assistance:

I’m reaching out to the Yunohost community for any advice or assistance you might be able to offer. If you’ve experienced a similar issue or have expertise in troubleshooting mail server authentication problems, I would greatly appreciate your insights.

Any guidance or suggestions would be incredibly helpful as I work to resolve this issue and get my Yunohost mail server back up and running smoothly.

Thanks in advance for your assistance!

Hi someonesusername,

Bummer. I scanned your linked thread aboud Roundcube;

Do I understand correctly:

  • using Roundcube as web-mailclient used to work, until it got broken by upgrade
  • something else(?) returns an error when trying to send emails

Which something else are you using to send emails?

What do you mean by this?

More concrete:

  • What client are you using?
  • Which element in the chain/process returns the error?
  • Maybe a screenshot of the error?

My Roundcube had problems during upgrades too often. I got it still installed, but switched to a combination of Snappymail and Cypht for webmail. Cypht is promising and ‘refreshing’, but Snappymail would be my first recommendation to install in a pinch when Roundcube got ill and your desktop/phone client refuses service.

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