Activ8 was an oversubscribed mess when I last had anything to do with it 20 years ago. It was also the only satellite provider in town at the time. Now I understand they are an NBN reseller with all the oddities their system entails.

However that does not really help you, but without the exact error messages you receive when you attempt to send mail and the settings for your outgoing server (SMTP) in account settings about all I can do is commiserate .

This is the message I receive. AS far as I can see all the account settings are OK.(Sending of the message failed. The message could not be sent because connecting to Outgoing server (SMTP) activ8.net.au failed. The server may be unavailable or is refusing SMTP connections. Please verify that your Outgoing server (SMTP) settings are correct and try again.)

I asked what the settings you were using were. Not if you thought they were Ok.

These settings would struggle in this day and age as they setting are from a bygone time. Just list the classic FJ, they "should still work", but decades have passed since they were considered either industry standard or vaguely secure.

So we come back to where I was before your reply when I asked what your SMTP settings were. Are you using connection security other than none. That is the only thing activ8 appears to support, is none. Thunderbird will try and use encrypted communications by default as it has been industry standard for about 20 years now. Having it set to none does reduce the support costs though because it is another thing that will not go wrong.

The next thing is they recommend using port 587 to submit mail. Port 587 is the default, modern SMTP (Simple Mail Transfer Protocol) port used for secure email submission typically requiring authentication and using STARTTLS encryption to secure data in transit. Yet activ8 not only do not mention STARTTLS they explicitly say not to use SSL/TLS. They do still offering instructions for using incredimail, it shut down in 2020 and ceased to work entirely in March of 2020, so I guess it would be expecting a bit much of them to have current setting or offer consistent information.

The page starts with

ACTIV8.NET.AU - Incoming (POP) Mail Server details Account Type POP UserName Your Email Address (For Ex: user@domain.com) Password Your Email Account Password Server hostname mail.activ8.net.au ServerPort 110 Required Authentication? Yes, Email account Username and Password SSL/TLS NO ACTIV8.NET.AU - Outgoing(SMTP) Mail Server details Account Type SMTP UserName Your Email Address (For Ex: user@domain.com) Password Your Email Account Password Server hostname mail.activ8.net.au Server port 587 Required Authentication? Yes, Email account Username and Password SSL/TLS NO

further down the page they have a change of heart and advise the setting to be;

IMAP port settings for ACTIV8.NET.AU Incoming Port: 143, Outgoing Port: 587 Secure - Port: 993 and Security Type: SSL/TLS (Accept all certificates) Insecure - Port: 143 and Security Type: None (Accept all certificates Not ticked: This server requires an encrypted connection (SSL) Use the following type of encrypted connection is None Note: If you use Secure SSL / TLS Settings, check the “This service requires a secure connection (SSL)” box in both outgoing and Incoming mails. POP port settings for ACTIV8.NET.AU Incoming Port: 110, Outgoing Port: 587 General settings for POP Secure - Port: 995 and Security Type: SSL/TLS (Accept all certificates) Insecure - Port: 110 and Security Type: None (Accept all certificates) Not ticked: This server requires an encrypted connection (SSL) Use the following type of encrypted connection is None General SMTP port settings for ACTIV8.NET.AU Outgoing (SMTP) Secure - Port: 465 for and Security Type: SSL/TLS (Accept all certificates) Outgoing (SMTP roaming server) Secure - Port: 587 and Security Type: SSL/TLS (Accept all certificates) Outgoing (SMTP) - Port: 25 and Security Type: None (Accept all certificates) Outgoing (SMTP roaming server) Insecure - Port: 587 and Security Type: None (Accept all certificates)

so as I can not get anything consistent from the provider as to what their expectation for connection are I tried testing the server configuration. my prefered site has changed so i wended up here https://www.checktls.com/TestReceiver

What I learned there is the certificates offered were self signed, so will be unacceptable to Thunderbird without manual intervention to verify the provided certificate is Ok. So I am back to making sure that the connection security of none.