I am trying to use the cloudflare mailchannels plugin for my cloudflare pages. But even though I set up everything exactly as described, including the Domain Lockdown, I do always get the following result:
Could not send your email. Please try again.
How can I find out what is going wrong? I can't find any log messages or other details.
I was having the same problem but was able to get it working with the info provided in this post. I added cfid=myproject.pages.dev and cfid=mycustomdomain.com to the _mailchannels DNS record that you set up as part of Domain Lockdown. Originally I had followed these instructions and used the generic workers.dev domain for my account.