POP3 mail is the only account that is assigned to the /bin/FALSE shell. However, ASSIGNING bash shell to the POP3 mail only gives user login access, which is always avoided. /bin/nologin can ALSO be used for the same. This shell access is provided to the user when we don’t want to give shell access to the user. The user cannot access the shell service and it rejects shell login on the server as in Telnet. It is mainly for the security of all shells.

POP3 is basically used for downloading the mail to the mail program. So for illegal downloading of all emails on the shell, this account is assigned to the /bin/false shell or the /bin/nologin. These both shells are the same as they both do the same work of rejecting the user login to the shell.

The main difference between these two shells is that the false shell shows the incorrect code and any unusual coding when a user login to the shell. But the nologin shell SIMPLY tells that no account is available. So nologin shell is used OFTEN in the Linux.