Today, users of the Mailgun transport enjoy the ability to send email to a "sandbox", where they are sent to Mailgun but not delivered. This provides a valuable tool during Rock testing to verify that no problems occur when sending out very large (recipient-wise) communications (like what slipped through recent v17 testing and resulted in 17.4... ahem.)

SendGrid has a similar feature https://mailtrap.io/blog/sendgrid-sanbox-mode-tutorial/ but if I'm reading it correctly, the SendGrid transport in Rock would need to be modified to optionally send the "sandbox_mode enabled" code.

I could imagine this just being a "sandbox mode" checkbox within the SendGrid transport config, with appropriate helptext indicating that NO MAIL WILL BE DELIVERED if enabled.

Why are we asking for this? We're an avid Rock alpha-testing org, and we use SendGrid. Having this sandbox feature would greatly increase our ability to actually test the transport we use against new versions of Rock.

Today, we point our test instance at Mailtrap, which is great for testing one-offs and preventing the instance from sending automated emails to real recipients... but since we have to use the SMTP transport to use Mailtrap, it's not a REAL test of a REAL production transport.

I'm not a dev and could be missing something obvious, but it seems like this would be pretty trivial to implement.