How to use text block in email newsletter? (with mymail plugin)

Hello,

I have bunches of newsletters sent to reader each day, that would be great if I can insert shortcode of textblock in the email content so I don’t have to adjust each email.

I use MyMail Plugin to send newsletter (a very famous self-host newsletter for wp), but when I inserted the shortcode of textblock in the email content and sent, there was just a blank at that area in the test email.

Please help if you can.

P.s. MyMail is a premium plugin so if you need the source code to test please contact me via email [email protected]