I have new installation of SBS2003 with EXCH2003 on one and only server machnine in company. There was recomendation to set domain name to "mycompany.local". Will this OK for sending and recieving mails and using OWA? (We have 5 users only). I understand, we must set MX record of our domain to WAN IP of our internet connection. Is there other native microsoft solution to leave domain basket in our ISP and load messages throught pop3 like with kerio or 602mail? Thank's

yes, you will still be able to send / receive mail using the public domain. You just need to change the email domain of your default recipient policy in ESM to the public domain name. see kb249299 Exchange 2003 SBS has a native, inbuilt POP3 connector which you should use for downloading email from the ISP pop3 hosting server and place it in the exchange mailboxes.

Thanks for your answer. Do you can describe me, how to set up that native inbuilt POP3 connector, please? (Because I found there any POP3 connector, but I thought (in documentation I have read it)it is only for connecting of POP3 clients, like Outlook Express, to exchange mailboxes)...

It is entirely possible to go this route but it is less than ideal. You are best off setting up the proper DNS records on the internet and having the mail routed directly to your server. If you are concerned about reliability and want the safety of being able to have your ISP catch the email if your server is down then you can set up a mailbox at the ISP for every user as well as a POP3 connector for every user. Then you can use a backup MX record to route the mail to the ISP and retrieve once the mail server comes back online (internet outage, power outage, hardware failure, configuration problem).If you need help setting up DNS and don't understand how this works, please post back here and we will tell you how to configure your WAN DNS. LAN DNS is configured by the SBS automatically during the initial wizard configuration.It is really important to configure your DNS properly though so that you can take full advantage of your new server and also so that you can receive email messages in a timely fashion. Much to many's beliefs on the internet, email delivery in a properly configured email system should be nearly instant (possibly a 3 second delay). If you configure using the POP3 connector then there will be at least a 15 minute delay until you receive any incoming messages (depending on where they fall in the retrieval interval).