If you manage multiple vendor relationships you probably have quite a few different points of contact in aggregate. It's hard enough keeping track of them all in general and given attrition, promotion, & book-of-business updates, your point of contact might change several times during the course of your relationship with the vendor.
To avoid digging through my email to find my last thread with a vendor I started using a simple doc that I filled in when I joined a company and then religiously updated as my point of contact at a vendor changed.
I also used this as a way to keep track of how to reach technical support (especially for vendors that require ticket submission via a website vs email & those with quirky support aliases I always forgot)
Template below & linked here. Clone & enjoy!