Hi Ray,
I'm not able to replicate an issue with spell check in SmarterMail 15.7.6970 or the supported version, Build 7008 (Mar 10, 2019). Please be aware that version 15.x is considered a legacy version, so I'm afraid I can't advise contacting support for this issue. I'd recommend that you consider upgrading to the latest build for this fix as well as many other fixes and new features.
Andrea Free
SmarterTools Inc.
877-357-6278
www.smartertools.com