This guide helps resolve an email sending error of type "the recipient has been rejected by the server" / "recipient rejected" (code: 550 5.7.1 relaying denied) or "authentication required" / "proper authentication required".

Resolve a Relaying denied error

Check that the parameter "My server requires authentication" / "My outgoing server (SMTP) requires authentication" has been activated in the settings of your outgoing server (SMTP) on the email software used.

You will generally find this setting under one of the following sections:

• "More Settings"
• "Advanced Settings"
• "Outgoing Server (SMTP)"

After correcting this parameter, it is important to delete or move pending messages in your outbox, then try sending a new message.

Use config.infomaniak.com

You can use the Infomaniak configuration tool to help you (log in to your Infomaniak account if necessary).

Also refer to this other guide for resolving errors.