You can pre-select a Conga Email Template by copying the template's
record ID to the clipboard and pasting it into your Composer button's URL following the
&CongaEmailTemplateId=id parameter.
An abbreviated parameter name, &CETID=id, may be used instead.
Note:
You may only specify one Conga Email Template Id per Composer button / link.
If you specify a Conga Email Template Id, but not a file template id (&TemplateId), Composer will display the list of "Conga Email Templates" (with the selected email template) by default.