how can send email by default

hello, i want to ask how users of uddeim can send message with sending email by default? i mean that when someone receive a message, not want to change his option for recieve message by email?

to clarify my question is how a user to send pms with email function with out the user can change his option for take messages with out mail functions

In the backend there is an option to enable email notifications by default.
This option is only valid for new accounts (strictly speaking for users who visiting their mailbox the first time).

The FAQ explains how to set this option for all accounts.

yes for working this i must have Allow e-mail notification : yes and Default for e-mail notification: always but my problem is that like that in frontend there is an option button which every user can change his option. if i want the user to cannot change his option what must i do? if i will make Allow e-mail notification : no maybe i will hide the option button but email notification it will be off and i want it on. that is my question

No, that is not possible without code changes.

what must i change in the code for hide this option button?