User Unsubscribed from Automated Workflow


I have set up automation on a sheet to email spacific people when lines are added, some of them have complained they are not recieving the emails and when i looked into the Activity Log it shows User Unsubscribed from Automated Workflow. When I checked with the user they dont recall doing so and were actually Out of Office on the day Smartsheet says they unsubscribed, could it be that their Out of Office Automatic reply is being recieved as an Unsubscribe request?