tput
is a command that uses terminfo(3)
(or termcap(3)
, depending on the system) to get the escape sequence that your interactive terminal uses to produce bold characters on output. That is not applicable to an email message, as the terminal on the receiver probably will not be the same (mostly won't, as normally people read email with graphical tools, not text based terminals anymore)
There is no concept of bold text in email. There is in HTML or other document formats (e.g. RTF, Word doc, Word docx, etc.) So the bold text will not appear as such in most of the mail readers (many of the text readers will avoid the escape sequences coming in the message, so they don't garble the actual text display)
Is it so important to focus on some part of the message, can you mark it with something less device dependent *****>>>>like this<<<<*****?
If you insist to send your personal terminal escape sequences to indicate a bold text, that doesn't appear as bold anywhere else in the world, you'll receive a lot of complaints from people that get their screens garbled by your messages. Worse if those are to be automatically sent.