Every DULO shirt is machine-washable. Make sure you set the temperature to warm (40 degrees Celsius or around 104 Fahrenheit), or below.
Before you put the shirt in the washing machine, please remove the collar stays placed in the little pockets underneath the collar. If you leave them in, they might fall out during the washing cycle.
Once the washing is done, do not tumble dry. Just take the shirt out and hang to dry. Wear directly. Once you put it on, body heat will warm the fabric and straighten itself out. Your shirt will only look better as the day goes on ;)