I like this list of 57 options along with comments on when to use each:

https://www.forbes.com/sites/susanadams/2013/...

Here are the versions that use regards:

Best Regards – More formal than the ubiquitous “Best.” I use this when I want a note of formality.

Regards – Fine, anodyne, helpfully brief. I use this.

Rgds – I used to use this but stopped, because it’s trying too hard to be abbreviated. Why not type three more letters? OK if you’re sending it from your phone.

Warm Regards – I like this for a personal email to someone you don’t know very well, or a business email that is meant as a thank-you.

Warmest Regards – As good as Warm Regards, with a touch of added heat.

I've never received anything with the sign off kind regards, but that doesn't mean it isn't used in AE. It would certainly be understood.

... the jeans that went kaput, ...

:-)

Wo wird das so verwendet ?

Gerade in einem Verlauf von einigen Emails mit einem britischen Geschäftspartner gelesen:

Kind regards (die "normalen" Mitarbeiter)

With kind regards (der Chef der britischen Firma)

Dass es sich dabei um eine freiwillig Anpassung an "deutsche Verhältnisse" handelt, glaube ich eher nicht, da die deutsche Seite konsequent mit "Best regards" unterschrieben hatte. Wie verbreitet das ist, weiß ich natürlich trotzdem nicht.

Edit: Ich sehe gerade, dass das ja schon in #1 stand - ich hatte auf die Schnelle nur in patman's Liste nachgesehen - sorry!