That can happen if your email client isn’t setup to authenticate when sending outgoing email.
There should be a setting within your email client to tell it to use authentication whenever sending an outgoing email… though that’s often disabled by default.
Once you enable that, you should then be able to send emails.
Well, it’s not just that authentication is allowed, it’s required… there’s another checkbox you’re looking for, that tells your email client to pass in authentication each time it tries to send an outgoing email.
In Outlook Express, the option is called “My server requires authentication.” in Outgoing Mail Server Settings.
In Outlook, it’s “My outgoing server (SMTP) requires authentication” in the Outgoing Server tab.
In Thunderbird, you have to check the box next to Use name and password in the Security and Authentication tab.
There’s different ways it’s done in the various mail clients, and the various versions of them that have been released over the years… but if you get Relay Access Denied when trying to send an email, that’s an indicator that your mail server doesn’t think your client authenticated.
The same client is working with a domain hosted on another server running CENTOS managed under CPanel, so I think it is a configuration issue between Ubuntu and Virtualmin.
Seems something is wrong with the sasl authentication daemon.
Is there a specific reason why you’re using the three years old Ubuntu 8, and not Ubuntu 10? I’m using the latter and email works perfectly there on a fresh install.
This is interesting: I did an upgrade to 10.4 LTS and that did not fix the problem.
I took the server offline, had our hosting company do a fresh install of the 8.04 LTS, did the update to 10.4 LTs and only then installed Virtualmin - and it worked.
Somehow, something is not working with Virtualmin on 8.04 and it is not fixed when you upgrade Ubuntu, but will work if Virtualmin is installed after the upgrade.
This took a night until 6 AM to work through, and I would still like to know what is causing this as I have another server on 8.04 to update.