Does K9 support APOP?
Yes, K9 supports basic MD5 APOP (RFC 1939). To configure K9 for use with APOP you need to enter details of the account(s) in the POP3 Server Check area of the Advanced tab. You do not need to actually enable the account in this section, you simply need to fill in the the regular server name, port, username and password so that K9 will know which password to associate with the provided account details when connecting to the remote server. The username in this section will be you normal username i.e. not the same format as used for K9 in your email program. Multiple different APOP enabled accounts can be configured by adding more accounts to the Server Check section.