Not fully. Generally, if you set in avast
PopListen=127.0.0.1:9110

and an account of your mail program looks like
POP server: 127.0.0.1
POP username: NAME#SERVER:PORT
POP port: 9110

The mail program connects to avast and logins with the name NAME#SERVER:PORT and it causes avast to connect to address SERVER at port PORT and login with the name NAME.

If avast receives the username without #, it will use the DefaultPopServer and the full username.