Sprout Forms Notifications to Office 365 address failing I've got a few Sprout forms on a site that are functioning nicely. Data is being save and notifications are firing to 2 of the 3 addresses. The third address is an Office 365 mailbox on the same domain but hosted elsewhere.

I'v tried updating Craft's Email setting to the SMTP info provided by the IT company in charge of the mail but it's erroring out with:

SMTP Error: data not accepted.

Has anybody else had issues with this? A little Googling has led me to believe that this is a common issue. Wondering if anybody in the Craft community has dealt with it successfully.
This error could be caused by the relationship between the user used in your SMTP Email settings in Craft and the From Address set in your Form notification. Some Mail Servers don't allow the sender (From Address) to be different from the SMTP user. Can you confirm if your From Address is the same email address in your SMTP settings?

Additionally, you may want to update your SMTP settings to use Mandrill or Mailgun. Those services make it pretty easy to look at your sent mail and see if it's being delivered and can provide more insight into what is happening if it is not being delivered.