Hi @CSD_Accy
As @ian_roberts suggests above, you’re using your own from address but using QuickFile’s mail servers. You would either need to set up the SPF records or use your own mail server (which is the better option), otherwise your emails are likely to be marked as spam.
Your custom email address can be seen under Account Settings > Routine Emails (at the bottom)
To set your own SMTP details, go to Account Settings > 3rd Party Integration > SMTP settings
Take a look at this article which guides you through the steps:
http://community.quickfile.co.uk/t/improving-email-reliability/8904
If you need help, please let us know 