Debugging mail messages

Question

Web development

Good afternoon.

does anyone know how? (extension) you can debug email messages while they are being viewed in your email client.

something like a firebug but for an email client it would be great.
Two points are of particular interest - viewing HTML (to a lesser extent) and debugging JS (to a greater extent),

it is clear that the letter can be received through the web interface in the browser and already there, twist as you like, but debugging in the mail client is of interest.

it is also clear that it is possible to pick up a standalone java script with a debugger, however, a cross-platform method is being sought.

Which clients allow this to be done? what are the extensions for?

so far I have only found this
getfirebug.com/wiki/index.php/Chromebug_User_Guide

but that is only for funderbird, but what about other clients?
whether it is possible to start it somehow with outlook, apple mail?

Thank you.

Answer 1

Well, JS is not supported in email clients, that's for sure) so there shouldn't be any problems with its debugging.