Currently the from email address when emailing invoice is email-reckonone@reckon.com. This causes an issue with many email prgrams and it is rejected as spam / junk. Within the setting there is a mandatory field of 'reply-to'. This should be used as the from address as well, especially as the email template adds
"To reply to this email, please use the 'Reply' function or email <reply-to>"
If they currently reply to the email it would be sent to the above dummy address!
Unfortunately due to anti-spam (Dmarc Policy) we must use the Reckon email as the sender. This is common with most cloud apps. If the user replies to the email it should reply to your noted business address. If not, please contact our support team so we can resolve this for you.
Better yet, Reckon should allow their customers the choice to use bulk mail via Sendgrid (the current default), or the customer's own SMTP credentials. Using the customer's own SMTP means the email is much much more likely to actually get through, instead of being hung up as spam.