2/ Takže to funguje stejně jako OWA? Když pak v Outlooku odešlu e-mail, tak bude zaznamenán na serveru ve složce Sent Items? POP3 a IMAP je v tom případě zakázaný.

3/ Vyřešeno s tímto.

The default settings which don't enable relay on the receive connector are:

Permission Groups (tab)

Enable:
Anonymous users
Exchange users
Exchange servers
Legacy Exchange Servers

Authentication (tab)

Enable:
Transport Layer Security (TLS)
Basic Authentication
Offer Basic authentication only after starting TLS
Exchange Server authentication
Intergrated Windows authenication

We also use have added a bunch of servers to your anti-spam in the Exchange server which cuts down on about 98% of the spam we get without them.

Anti-spam -> IP Block List Providers

Providers:
dns.rfc-ignorant.org
sbl-xbl-spamhaus.org
bl.spamcop.net
dnsbl.sorbs.net
list.dsbl.org