<p>Postmark or received by?</p>
<p>This might be a better question to email to admissions. It most likely is postmark (do you still have the online option?), but I'd email.</p>
<p>you can reply online! apply.olin.edu, go to your decision letter and click the link at the bottom of the page.</p>
<p>Technically, May 1 is viewed as the postmark date and/or the receipt date for electronic submissions. This true (or should be true) for all colleges and universities, unless otherwise noted. </p>
<p>With regard to Olin, I would strongly encourage using the online response method! :D
Call me crazy/lazy, but we like it alot!</p>
<p>Good luck with all your tough decisions,
Allison</p>