It’s a clever tool. I had a thought that might make it even more effective for your international users like myself.
I’ve noticed that the warmup emails currently include a US phone number in the signature. As I’m based in the UK, I’m a little concerned that this might look like a small red flag to spam filters. We all know how sophisticated providers like Google are; they can easily see that my activity is UK-based, so a US contact number might seem inconsistent or unnatural to their algorithms.
My suggestion is to introduce country-specific contact details in the signature. So, for a user in the UK, a UK phone number would be used, a German number for a user in Germany, and so on.
I believe this small touch would significantly boost the authenticity of the warmup emails and improve deliverability for your entire global user base.
Thanks for considering it, and keep up the fantastic work!