I have used Evolution mail client and for outwards mail I selected the Sendmail option. This has worked fine mail goes out through Sendmail with no problems.
I would like to switch to Thunderbird email client but it does not appear to accept any outwards mail except via smtp. I would like to continue using the Sendmail as I have done in past.
How can I do this with Thunderbird.

ps I cannot use smtp as my email account is at one ISP and my broadband connection is with another firm. Neither firms will let me use their smtp servers as they both want me to have mail and ISP with the one ISP They block traffic from domains other than their own.

I install postfix on my system, then for the outgoing server in my email clients, I select "smtp" then the host is "localhost". The only problem with this setup is that some companies to not accept email from people running their own mail servers using dynamic IP's.