system
7
Okay. No problem . I´m using K9 with Thunderbird and AVAST!. To configure your email account you just need to use this settings:
In Account Settings / Server Settings:
Server name: 127.0.0.1
User Name: 127.0.0.1/110/username#pop.server.name
Port: 9999 (this is the port in k9)
You don´t need to change anything in SMTP configuration.
That´s it. I read this in other topic here.
Yeah Technical. I listened ! 
Bye bye !