Step Wise Manual So-net mail settings for thunderbird
If you don't have a So-net mail address. you can create an email id from here then you can So-net email login.
Open Thunderbird Software App. Click on Email
When you click on the email, pop-up Set UP an Existing Account Screen.
Enter Your name, So-net Email address and Password then press Continue.
Click on the Manual config menu at bottom.
Enter Below So-net incoming server settings.
In incoming click on the dropdown menu and select POP.
Add server host :pop.so-net.ne.jp
Port: 110
select SSL/TLS
Enter Below So-net outgoing server settings.
In outgoing select SMTP.
Add server host :mail.so-net.ne.jp
Port: 587
select SSL/TLS
Tap on Done. Now you are ready to use your So-net email account on your Thunderbird.