Following helpful replies from Kent(ktb) and Steve Gran to a request under the subject of 'email options', I've been looking further into the possibilities.
I want to try qmail which I've found and built. It will not install as it conflicts with ssmtp - seems I can have only one MTA. Dselect will not uninstall ssmtp as the MUA's 'will feel lonely'. So presumably I will have to either temporarily remove the MUA's and replace ssmtp with qmail ( I haven't tried that, but, even if it works, I don't like the idea as I want to try other MTA's until I find one I understand and like) or force dpkg to uninstall ssmtp. Both the man page and dpkg --help are unclear to me, and I don't want to risk damage. Could someone help with the precise syntax to force remove and purge ( ssmtp in this case ). Or am I labouring under a misunderstanding ( kmail, which I've used for a long time, doesn't appear to enter into the conflict). Grateful for any advice, John.