Dovecot versus Postfix

[Jan Sneep]

>From the Gnome desktop, under System -> Administration -> Services I can see
that both Dovecot and Postfix are up and running and both are shown as a
"Mail Agent".

What's the difference between the two? Do I need to have both running on the
server or is just one sufficient?

I have found pages at https://help.ubuntu.com/community for both. Dovecot is
described as a "Mail Deliver Agent" and Postfix as a "Mail Transfer Agent".
Does one rely on the other? Do I need to configure both?

I want to replace an old Windows mail server that came with Windows '95, and
yes has been working beautifully without so much as a single hiccup over the
past 12 years. It is used just to transfer mail to other users on the LAN,
actually just between my wife and I. Two mailboxes and we use it 90% of the
time just to send each other calendar appointments, so we know what plans
the other has made. The rest of our mail we send directly to our ISP's mail
server for delivery and we grab our incoming emails directly from the three
ISP mail servers that we have account on.

As a sort of secondary, but possible related question, I recently managed to
get eGroupware working and so we can now login and access the same contacts
database. This is great, however it doesn't seem to allow me to integrate it
into our old Outlook 2000. I want to replace Outlook with an open source
mail client. eGroupware seems to integrate with something called FelaMiMail.
Which I'm hoping will allow me better access to the contacts database so I
don't have to copy and paste addresses into my Outlook. So if I use
FelaMiMail would it be better to use Dovecot or PostFix ?

Can anyone help with these questions?

Thanks in advance,

Jan