In some cases, it can be helpful to save the email template separately from the document, e.g. if a single document is to be sent with different email texts. To do this, add 'c_check' for the corresponding letter in 'Details 2' in the 'Report Builder' and add an entry 'a_mails' with the email setup in 'Field Validation' for each document and language (example 'a_mails' / '024d' for letters or 'a_mails' / 'inv01d' for invoices).