A Linux Administrator assigns a POP3 mail-only account to the /bin/false shell. However, assigning a bash shell to a POP3 mail-only account gives the user the login access, which is usually avoided. The /bin/nologin shell can also be used. This shell is provided to the user when we don’t want to give shell access to the user. The user cannot access the shell, and it rejects shell login on the server as in Telnet. It is mainly meant for the security of the shells.
POP3 is basically used for downloading mail-to-mail programs. So for the illegal downloading of emails on the shell, this account is assigned to the /bin/false shell or the /bin/nologin shell. Both shells are the same as they 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 logs in to it, whereas the nologin shell simply tells us that no such account is available. Therefore, the nologin shell is used often in Linux.