Is it possible with sieve to :

1. get sender of an email
2. lookup if this sender is present in an mailbox
3. if the sender is known, change the subject of the email. if the sender is not known, do nothing.
4. put/leave message in inbox.

or maybe use dictionary (not really familiar with this)

1. get sender of an email
2. lookup if this sender is present in an dictionary
3. if the sender is known, change the subject of the email. if the sender is not known, do nothing.
4. put/leave message in inbox.

But then I need something like

1. if message is dragged into a specific mailbox/folder

2. add sender to dictionary

3. if message is removed from a specific mailbox/folder

4. remove sender from dictionary