mass mailing merge PDF password protect

[cazfordo]

hi. scenario:

1. 2500 individual employee letters need to be sent to them - somehow - but not by printing/posting ie stuffing envelopes and slooooow.
2. Letters are currently created using mail merge in word - they contain personal sensitive data;
3. Letters need to be individually saved rather than one big file ie 'Bloggs, Joe 2011May26'.
4. Letters then need to be PDF'd
5. Letters need a unique password per employee (ie national insurance number)
6. Letters then need to be sent to employees email ID for them to open / save using password.

Please tell me there is a tool(tools) that can help with this? It's driving me potty. We don't have to create in word - we can create fields in excel and merge to PDF alternatively. Alternatively we also use Ericol Lists/Sharepoint which means employees could possibly collect a PDF from a secure area (perhaps this is phase 2 though).

Help?