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Excellent explanation----thank you guys!
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---If I understand SMTP gateway or some call it SMTP relay, is where the anti virus and anti spam software is installed on the same box as exchange2003 (without mailboxes), so that emails coming in from internet are scanned before they are forwarded to the Front end server.<br />
correct me if I am wrong<br />
<br />
--emails going from inside to internet should not go through this SMTP gateway/relay, but have seen some configuration that make it go through it. what 's the reason ?<br />
<br />
---if possible, can someone tell me how Exchange Front end is able to determine such email has its user mailbox in Exchange server 1 and such email has its user mailbox in exchange server 2 &nbsp;???<br />
<br />
thanks
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---If I understand SMTP gateway or some call it SMTP relay, is where the anti virus and anti spam software is installed on the same box as exchange2003 (without mailboxes), so that emails coming in from internet are scanned before they are forwarded to the Front end server.
correct me if I am wrong

--emails going from inside to internet should not go through this SMTP gateway/relay, but have seen some configuration that make it go through it. what 's the reason ?

---if possible, can someone tell me how Exchange Front end is able to determine such email has its user mailbox in Exchange server 1 and such email has its user mailbox in exchange server 2  ???

thanks

Exchange SMTP relay/gateway

Exchange is the server side of a collaborative application product that is part of the Microsoft Server infrastructure. Exchange's major features include email, calendaring, contacts and tasks, support for mobile and web-based access to information, and support for data storage.

Exchange

Microsoft Outlook is a personal information manager from Microsoft, available as a part of the Microsoft Office suite. Although often used mainly as an email application, it also includes a calendar, task manager, contact manager, note-taker, journal, and web browser.