Dan Tsafrir

I believe hotcrp already does this so long as you don't use per-author fields (such as %NAME%, %FIRST%, %LAST%, and %EMAIL%) in the body or subject of the email --...

Hotcrp comments support attachments and their visibility can be set to 'eventually visible to authors (anonymous to authors)', so it seems this mechanism could be used.

Please see more information about this issue and how we eventually addressed it in Section 6 of https://www.usenix.org/sites/default/files/atc19_message.pdf

Thanks for the suggestions and for pointing out the ability to make fields absent and present per round! Unfortunately, for me, the drawbacks of your suggestions -- spreading the state...

If the submission ID is made unique across cycles (for all submissions, not just revise-resubmit), it would make searching for a specific submission easier, allowing us to use the same...