I wrote a Python application addrcollector for collecting email addresses from email messages. Addresses can be added by sending a message on standard input or my adding on the command line. Addresses can be retrieved by using a keyword. Old addresses are automatically purged. See the usage output below.

addrcollector: Collect email addresses for later retrieval, or                                                   
search the database of previously collected addresses.                                                           
                                                                                                                 
Usage:                                                                                                           
  addrcollector.py --add ADDRESS [NAME]                                                                          
  addrcollector.py --import                                                                                      
  addrcollector.py --search WORD...                                                                              
  addrcollector.py --help                                                                                        
                                                                                                                 
Options, arguments, and commands:                                                                                
  -a --add      Manually add an address.                                                                         
  ADDRESS       Email address to add to database.                                                                
  NAME          Name to associate with email address (optional).                                                 
  -i --import   Import addresses from headers of one message via standard input.                                 
  -s --search   Search database for addresses; multiple keys are ORed.                                           
  WORD          Search key.                                                                                      
  -h --help     Usage help.                                                                                      

Requires: python3-docopt, python3-xdg

addrcollector.py script