I have a requirement to attach pdf document with my emails. And the pdf document changes with each email according to the system configuration. 

Can you please help in understanding 

1. how can I upload my PDFs to EnhanchedFtp?
2. What is the retention policy in EnhancedFtp
3. how can I refer them in my email? I know I can use AttachFile function, but how can I pass my pdf name which changes with each email.