Hi,
It is a planned future improvement to make the email templates editable from the UI along with the option for html email, but not sure how soon that will be done.
Currently it is possible to copy the existing message template files, rename them and then point to the custom ones from config settings.
These config settings show the default values:
<add key="EventCalProCustomConfirmationBodyTemplate" value="DefaultTicketOrderConfirmationPlainTextEmailTemplate.config"/>
<add key="EventCalProCustomAnonymousConfirmationBodyTemplate" value="DefaultTicketOrderAnonymousConfirmationPlainTextEmailTemplate.config"/>
The files live the /Data/MessageTemplates folder, note that though config values do not have the language prefix, the actual files on disk must be named with the language prefix, ie on disk the files are:
en-US-DefaultTicketOrderConfirmationPlainTextEmailTemplate.config
en-US-DefaultTicketOrderAnonymousConfirmationPlainTextEmailTemplate.config
or if you are forcing a different setting like en-GB then you would prefix your files with en-GB- but again leave that part of the file name out of the config setting.
Which of the above 2 files is used depends on if you are requiring authentication for ticket purchases and whether the user is authenticated at the time of the transaction.
Hope that helps,
Joe