The ODK forum normally allows replies to direct messages via email. However, this currently does not seem to work.
Gmail says:
Delivery incomplete
There was a temporary problem while delivering your message to 73a-redacted-87e@forum.getodk.org. Gmail will retry for 19 more hours. You'll be notified if the delivery fails permanently.
The recipient server did not accept our requests to connect. Learn more at https://support.google.com/mail/answer/7720
[forum.opendatakit.org. 37.139.4.90: FAILED_PRECONDITION: connect error (111): Connection refused]