SharePoint Designer workflow triggering multiple emails.

I had a list containing 8 people picker columns with allow multiple values set to true. It was having out of the box forms. Whenever user submits an item it sends an email to all the users marked in all the people picker fields. SharePoint Designer workflow was used to send email to users. Workflow was having just “send an email action”.

Issue: Users were getting n number of emails on item creation/updation.

Workflow Status: Workflow was stuck in suspended state and keeps on retrying because of retrying users were getting n number of emails.

Reason: For an item is number of total users in all people picker column reaches approx. 30 or more and where few duplicate users are added in multiple fields. Then the “send an email” action tends to go to suspended state and keeps on sending emails to users marked in people picker column until the workflow is terminated.

Solution: There should not be repeated users in multiple people picker fields. For ex. User1 Should not be present in Field1 & Field2 simultaneously.  For that you can add a client side validation before item submission notifying the users whenever there are any repetition of users.