# Using the POP3 Client Capabilities

The Post Office Protocol—Version 3 (POP3) allows a client application to access email that is stored on a POP3 server. The client application must provide a user name and password to access email from an account on the server.

The LabWindows/CVI Internet Library provides functions that allow an application to open a connection to a POP3 server, retrieve email messages and information about these messages from the server, remove messages from the server, and close the connection to the server. LabWindows/CVI also provides parsing capabilities, so you can obtain the value of a specific field in the message header.

The Internet Library does not support parsing and detaching attachments. The attachment data is returned along with the rest of the body. You can parse the body of the message for the attachments and decode the attachments if needed. Typically, the attachment data is inserted as MIME blocks and encoded in base–64 and other formats.

| Note Some POP3 servers may close a connection based on a custom idle timeout period. Therefore, National Instruments recommends that once you open a connection to a POP3 server, you issue commands, retrieve messages, and close the connection as soon as possible. If the POP3 server closes the connection, subsequent POP3 function calls using that connection handle will return kInetSocketError (System socket error).