(Added in V6.12)

When the IMAP4 CAPABILITY command is received, VPOP3 generates a capability string based on settings, then calls

DoCapability(ipaddr, capabilities)

* ipaddr = IP address of the client computer
* capabilities = generated capabilities (a space is added at the beginning and end to make finding words simpler)

The function should return a new capabilities string. To do nothing, return the 'capabilities' argument. You can remove capabilities from the string by using string modification functions. We do not recommend adding capabilities as they will not be supported by the rest of the IMAP4 service, so could lead to email client problems.

e.g.

function DoCapability(ipaddr, caps)
  --Remove IDLE from the list of capabilities
  caps = string.gsub(caps, " IDLE ", " ")
  return caps
end