You need to pipe the output of your script to pbcopy
pbcopy
For example:
./somescript.sh | pbcopy
echo 'your-email@example.com' | pbcopy(as @Jonathan Leffler stated above)
echo 'your-email@example.com' | pbcopy
Or see the answer for the related question on piping to clipboard on different operating systems:Pipe to/from the clipboard in Bash script