Symptoms

When a user sets themself as "out of office" in Outlook, the automatic response generates the SmartActions error "The message you provided was not understood by the server. Ensure that the serial number of the task is included in your reply. You can find this in the original notification or on your K2 worklist. You can reply with 'Actions' to get a list of actions."

 

Diagnoses

The way that SmartActions currently works is it polls the mailbox at regular intervals using EWS and looks for any new items. If new items are found, it attempts to process them. This includes any emails that are not strictly SmartActions.
 

Resolution

With the "Out of Office" automatic replies in Outlook, by default it adds "Automatic Reply: " to the email subject line. Open Outlook as the SmartActions email account and created a folder below "Inbox" called "Out of Office". Create a rule that searches for "Automatic Reply" in the subject line and sends it to the "Out of Office" folder. (This does not affect all messages with the words "Automatic" and "Reply" in the subject, only the full string)

The SmartActions account will only sync the Inbox, and not any subfolders, so the automated replies are not responded to.