fetchmail in "system-wide mode"

[Xavier FreeBSD questions]

Hello,

On the Internet there are some sites where they say to start fetchmail(1) in
"system-wide" should put these two options in rc.conf(5) :

fetchmail_enable="YES"
fetchmail_polling_interval="60"

Although the second is optional and at first has little to do with this
question because this question is addressed rather to the first option.

I searched in /etc/defaults/rc.conf and rc.conf(5) manual and find no
reference to these two options.

I have them in my rc.conf(5) but fetchmail(1) does not start automatically.

In /usr/src/UPDATING not found any reference to it.

Which is the correct way to start fetchmail(1) in "system-wide"?

Thanks.