clean-imap-inbox.py

# This script will log into the specified IMAP server, select the INBOX, 
# then just delete all the messages present there.
import imaplib

the_imap = imaplib.IMAP4_SSL("your-imap-server.com")
print(the_imap.login("your-login", "your-plaintext-password"))
print(the_imap.list())
print(the_imap.select("INBOX"))
typ, data = the_imap.search(None, "ALL")
msg_set = data[0].split()
if msg_set:
    msg_set_str = "%s:%s" % (msg_set[0], msg_set[-1])
    the_imap.store(msg_set_str, '+FLAGS', '\\Deleted')
    the_imap.expunge()
print(the_imap.select("INBOX"))
the_imap.close()
the_imap.logout()