The POP3 Client Lua Script is called POP3CLT.LUA and is edited in Settings → Scripts. This script is called whenever VPOP3 runs a POP3 session to download messages from a remote POP3 server.

VPOP3 will call the following Lua functions in the script at the following times:

• Start() - called when the POP3 session starts, before VPOP3 starts downloading any messages.
• DownloadRules() - called before each message is downloaded to determine how VPOP3 should handle the message. A scripted version of normal Download Rules in VPOP3.
• StartMessage() - called just before VPOP3 starts downloading a message from the remote server.
• MessageLineRaw() - called when VPOP3 has downloaded a line of a message from the remote server.
• MessageLine() - called after VPOP3 has processed a line of a message from the remote server,just before it saves it.
• EndMessage() - called when VPOP3 has finished downloading a message from the remote server.
• ProcessMessage() - called after VPOP3 has downloaded a message from the remote server to determine if any special actions need to be performed on the message.
• End() - called at the end of the POP3 session.