Enabling POP3 and IMAP4

Exchange Server 2007 supports Internet Message Access Protocol 4 (IMAP4) and Post Office Protocol 3 (POP3). IMAP4 is a protocol for reading mail and accessing public and private folders on remote servers. Clients can log on to an Exchange server and use IMAP4 to download message headers and then read messages individually while online. POP3 is a protocol for retrieving mail on remote servers. Clients can log on to an Exchange server and then use POP3 to download their mail for offline use.

By default, POP3 (version 3) and IMAP4 (rev 1) are disabled in Exchange Server 2007 and no longer have associated HTTP virtual servers. This is primarily because Outlook Web Access, Exchange ActiveSync, and Outlook Anywhere offer so much more that they are the preferred way for users to access Exchange Server. If you still have users who want to use POP3 and IMAP4 to access Exchange Server, you can configure this, but you should try to move these users to Outlook Web Access, Exchange ActiveSync, or Outlook Anywhere.

To enable POP3 and IMAP4, you must first start the POP3 and IMAP4 services on the Client Access servers that will provide these services. You must then configure these services to start automatically in the future. You must also configure Simple Mail Transfer Protocol (SMTP) for your POP3 and IMAP4 clients to send e-mail.

You can enable and configure POP3 for automatic startup by completing these steps:

1. Start the Services utility by clicking Start, selecting Administrative Tools, and then selecting Services.

2. Right-click Microsoft Exchange POP3, and then select Properties.

3. On the General tab, under Startup Type, select Automatic, and then click Apply.

4. Under Service Status, click Start, and then click OK.

You can enable and configure IMAP4 for automatic startup by completing these steps:

1. Start the Services utility by clicking Start, clicking Administrative Tools, and then selecting Services.

2. Right-click Microsoft Exchange IMAP4, and then click Properties.

3. On the General tab, under Startup Type, select Automatic, and then click Apply.

4. Under Service Status, click Start, and then click OK.

For users to be able to retrieve mail using POP3 and IMAP4, you must also configure SMTP. POP3, IMAP4, and SMTP require you to open the ports shown in Table 16-2 on your organization's firewalls.

Table 16-2: Standard and Secure Port Settings for Messaging Protocols
Open table as spreadsheet

Protocol	Default Port	Default Secure Port
SMTP	25
HTTP	80	443
IMAP4	143	993
POP3	110	995

In Exchange Management Shell, you can mange POP3 and IMAP4 using the following cmdlets:

• Get-POPSettings Lists POP3 configuration settings.

• Set-POPSettings Configures POP3 settings.

• Get-IMAPSettings Lists IMAP4 configuration settings.

• Set-IMAPSettings Configures IMAP4 settings.