How to send email with EC-21

I have success with send and receive SMS and sending MMS images with EC21. It works well.

Is there a document to explain how to send email body text?

Dear Sir,
Thanks for your inquiry in Quectel forum.
For your issue, it is better to tell me the firmware version of your module used now. Thanks!
The following is the reference document about SMTP, you can check it. Thanks!
Quectel_EC2x&EG9x&EM05_SMTP_AT_Commands_Manual_V1.0.pdf (329.7 KB)

Thank you.

Firmware is EC21AUFAR06A01M4G