Under an iPlanet 4.1 SP11 web server, with PHP compiled as an NSAPI module, imap_open() always fails. It does not even attempt to make a connection to the IMAP server. However, the same code, executed in the PHP CLI works perfectly.

Here is a sample of a script that does not work under the NSAPI module, but works under the CLI:

<?
  imap_open("{srv.abc.com:143/imap}INBOX", "user", "pass");
  print imap_last_error();
?>

When run under the NSAPI module, the following error is generated:
Warning: imap_open(): Couldn't open stream {srv.abc.com:143/imap}INBOX in /usr/SUNWips/public_html/agtest.php on line 2
Can't connect to srv.abc.com,143: No such file or directory

The remote IMAP server is an iPlanet Messaging server, but this is irrelevant as traces have shown that the connection is not even attempted when running as NSAPI.

A truss revealed only that once connect() is called, in the success case (the CLI) time() and poll() follow, but under NSAPI, close() immediately follows the call to connect().