Ubuntu Server -Send mail with the info resulting from a command

I have this command to see the space of my hard disk of my server: fdisk -land I do a grep to filter more the information that interests me (my main HD):

The command looks like this: fdisk -l | grep vda, and to this I put the header of what each number is (the title) : df -h | grep -m1 "" && df -h | grep "/dev/vda1 ", being as follows ->

Ok, once I have the information I need, I have a script to send emails, which works like this:

enviar_email.sh "(destinatario)" "Titutlo" "Cuerpo Mensaje"

So, the recipient and the Title are covered, but the body of the message I want to send the output of the previous command.

What I have tried without success is:

./enviar_email [email protected] "Un Asunto" $(df -h  | grep  -m1 "" &&  df -h | grep "/dev/vda1 ") 

But the empty mail is sent to others because the command that creates the body fails. What I am trying to do is redirect the output to the style : echo "hola" > hola.txtbut as a parameter to my script.

I don't know if it's because that command doesn't give usable output and if so I don't understand how I could capture it and send it in one step.

And I want to avoid at all costs having to, prior to the script, create a file with the content of the script's output and read it when sending email, I think it's unnecessary.