This issue occurs when the POP3 e-mail server that is specified in the properties for either a global or individual POP3 server contains a fully qualified domain name (FQDN) that is longer than 32 characters. Note that this includes the periods between FQDN components.
To resolve this issue:
Use a text editor such as Notepad to open the "hosts" file that is located in the %windir%\system32\drivers\etc folder.
Add the following entry to the end of the hosts file
where X.X.X.X is the IP address of your POP3 server. Use the "mail.local" entry to avoid name conflicts with existing DNS names. Save the file and then quit the text editor program.
NOTE: You must modify this file again if the IP address of your POP3 server changes.
Click Start, point to Programs, point to Microsoft Exchange, and then click Microsoft Exchange Administrator.
In the left pane of the Exchange Server Administrator program, view the following object:
In the right pane, double-click Connector for POP3 Mailboxes to view its properties.
Click the entry for your POP3 mailbox, and then click Edit. Change the entry for "POP3 Mail Server" to "mail.local" (without the quotation marks). Click OK, click Apply, and then click OK. Note that the change is effective immediately.
Microsoft has confirmed that this is a problem in Microsoft Connector for POP3 Mailboxes that runs with Exchange 5.5 on Small Business Server 4.5.
The FQDN name length of the POP server problem has been corrected and is no longer a cause for these errors in the Microsoft Connector for POP3 Mailboxes that runs with Exchange 2000 on Small Business Server 2000 or 2000 Service Pack (SP) 1.
If the errors occur with the Microsoft Connector for POP3 on Small Business Server 2000 or 2000 SP1, see the following Microsoft Knowledge Base article:
327672 Error Message When You Are Using the Microsoft Connector for POP3 Mailboxes to Download E-Mail Messages