Sender authentication is critical for accounting related communications. There have been multiple instances of fraud impersonating Reckon account domains and emails. Adding DKIM will allow for improved sender authentication from the Amazon SES service.
Reckon utilise Amazon SES for outbound email sending across their cloud and hosted product range.
Further Amazon themselves reccomened DKIM is setup on their services:
https://docs.aws.amazon.com/ses/latest/DeveloperGuide/send-email-authentication.html
This is an absolutely critical feature requirement for most enterprise email security policies to accept incoming email.
Update: We tested DKIM for Reckon Hosted previously and found no improvement in sender authentication. However we agree that although the results proved unsatisfactory, adding DKIM will not have any adverse effects. Therefore after this years code freeze (post the 2020 release) we will turn on DKIM for the hosted service.
Update 15 June 2020: In place for Reckon One. We will review Reckon Accounts Hosted.