Which MTA is installed on a given machine?

[stan]

I have several Ubuntu machines at work. They are all relatively current as
far as updates. We are making some changes in our domain, and I need to
reconfigure the MTA on these machiens. How can I figure out which of the
several possible MTA's are installed on each amchine?

Once I know that, it;s just dpkg-reconfigure <pakcage name> to reconfigure
tor fowarding, domain name chabges etc. right?

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