I'd like some suggestions as to how to best go about creating an application which can generate bespoke automated e-mails- i.e. send a personalized reply to a particular individual, interpreting the context of the message as intelligently as possible...

(This is perhaps too big a question to be under one title?)

What would be a good starting point? What concepts do I need to know? I'd imagine that the program needs to be able trawl through e-mails as and when they come in, and search for keywords in e-mail content, in order to write an appropriate reply. So there needs to be some form of automated response embedded in the code.

Machine learning and databases come to mind here, as I'm aware that google incorporates machine learning already in gmail etc.

It is quite tricky to google the above topic, and find the perfect tutorial. But there are some interesting articles and papers out there:

Machine Learning in Automated Text Categorization (2002) by Fabrizio Sebastiani , Consiglio Nazionale Delle Ricerche

However, this is not exactly a quick start guide.

I intend to add to this question, and no doubt other questions will spark off this one.

I look forward to suggestions.