There are few a reasons why your invoice ends up in the junk folder, @Vishal1. I'll share some of them as I provide a workaround for you.
The email domain of your customer is likely restricting @intuit.com, which is why some emails from QuickBooks Online were flagged as spam. In this case, you'll want to advise them to select This is not spam or Not Junk when they find your email in their spam folder.
Additionally, you'll want to inform them to add quickbooks@notification.intuit.com to their contacts or send a sample email to do not reply@intuit.com. This makes it easier for their email provider to identify the @intuit domain as a reputable website.
Feel free to read these resources to learn more about QuickBooks Online email server hostnames and IP addresses:
Wow, I am amazed about this 'blame' the customer response! We have just started sending out invoices and they immediately go to junk!?! What Intuit? How is it possible we can set up marketing campaigns and have all authorised mail senders included in our SPF records but Intuit cannot guide or provide a decent solution that will allow their clients to send invoices in the knowledge that they will arrive?
Please advise what DNS config we should use that will allow us to send invoices without them going to junk?
At present I have added "include:e.notification.intuit.com" as this appears to be the sender, however, there is only a hand full of servers behind this so are there others? Perhaps we could have a list of IP addresses so we don't surpass the max to lookup limit?
I understand the convenience of working your invoice emails without any issues, lostdutchman. Let me help you configure your server to accept QuickBooks Online mail server hostnames and IP addresses.
Many email servers won't accept messages from IP addresses that don't have reverse DNS records that correspond to the domain name that the server claims to represent. This is an anti-spam strategy that stops spammers from posing as well-known domains.
Since this requires technicalities on your end, it is best to work with an IT professional to help configure and accept QuickBooks Online mail server hostnames and IP addresses to allow invoice emails to transit via your mail servers. Thus, you can follow Solution 3: Configure server to accept QuickBooks Online mail server hostnames and IP addresses outlined in this article: Troubleshoot if customers aren't receiving emails from QuickBooks Online.
We're here to back you up in this forum if you require additional assistance managing sales transactions. Please let us know in the comments below. Stay safe!