change Mail folder location?

Hi gang. I'm sure I'm not the only one with this issue. My OS is on an SSD partition. I have several much larger HDDs attached. MAIL currently is already taking up about 25% of my OS SSD partition and growing. Yet there does not seem to be any obvious way in Mail preferences to place the mail folder anywhere except where the system lives. Am I missing something? Back when everything was HDDs it didnt matter really, but now that we all want our OS and apps and caches on SSD it makes zero sense to clog up that expensive SSD with this giant mostly dormant database folder. I understand there are probably symlink style hacks one could do, but are there any actual Apple solutions? I'm currently on High Sierra still, so if this is improved in Mojave or Big Sur I would like to know that as well. Thanks!