All that the documentation says is the following:
The subject indicates the subject on the current email. <aura:attribute name="subject" type="String" /> The messageBody indicates the email message on the current email. <aura:attribute name="messageBody" type="String" />
I assumed that I could write to thse fields because the Lightning for Gmail Application itself can write to the Gmail body and subject fields using the template component. However, when I try to set the aforementioned attributes, I can only register the changes in my custom component; the Gmail fields in the email composition modal stubbornly remain unchanged. Does anyone have a definitive answer or another way to write to the Gmail body and subject fields using the a custom component in the Lightning for Gmail application? Thanks in advance.
(same question was asked over a year ago here and received no responses)