Sending email from Java 5 via Lotus Notes

Hi There,  

I support an old Java Web Based application (not quite J2EE compliant) that sends emails via Lotus Notes.  Our set up is that we have a Lotus Notes client (and ID file) installed on our Web Server (using WebSphere 3.5).  We also have Lotus Notes API for Java (based on Lotus Notes 5).  This means our Java code only need to "fill" in a few fields and call a method from the Lotus Notes Java API and the message is automatically routed out to the Lotus Notes client (and from there is becomes a "black box").  

We now have a initiative to bring our Java code from version 1.2.2 to JSDK 5 and EE 5 (or J2EE 1.4, not sure which yet).  Part of my task is to create a qoute on how long this will take to do.  The customer will not want the code rewritten too much, only remediated.  What I am stuck on now is will I need to get a updated version of the Lotus Notes Java API to run under JSDK 5 and EE 5?  Has the interface to Lotus Notes from the Java langauge changed a lot so that now a API is not used (i.e. will we need to do a rewriting in our application to get the email functionality to work).  If I do need a new API where is it available from?

At this stage the Lotus Notes Client on the Web Server will most likely be upgraded.  

I saw a another question based on this subject but it was dated 2001.  

Thanks, Goatofdean.