Q: I have a frustrating issue whereby I can open encrypted files that have been sent to me by another PGP user on email, but when that same user uploads files to an FTP site I cannot decrypt any of the files. Even though it's the same person encrypting them. What's going on here?
A: Whether or not you can decrypt an email or file has nothing to do with the senders key. It depends on whether or not the content is encrypted to your public key. The email is being correctly encrypted to your public key because the sender is probably using the PGP Email Proxy in PGP Desktop which automatically selects the key that has the email address to which the message is being sent. When the sender is encrypting the file prior to placing it on the server s/he is very likely only encrypting to their own public key and not yours. You'll need to ask the sender to add your public key when encrypting the files. This is done in the PGP Recipients window that pops up after the file to be encrypted is selected.