Hi Tom -
To re-generate an email report, run the following api call (for example):
https://qa-reports.linaro.org/api/builds/11844/email?template=9
There are a few allowed arguments. template is one, whereby you can specify any template stored in squad (viewable at https://qa-reports.linaro.org/api/emailtemplates/). You can also specify a 'baseline' build to use for regression and fix detection. This actually allows you to compare arbitrary builds against one another, even across branches (only you know if it makes sense to ever do so, but sometimes it does!)
So for example, this URL gives the latest 4.19 results compared to the previous 4.19 release (by setting baseline):
https://qa-reports.linaro.org/api/builds/11864/email?template=9&baseline...
Since it's a little bit of a hassle to look up build ids (to do it manually, start at https://qa-reports.linaro.org/api/, then click on projects, select the project you want, then click builds, then find the build id for the build you want to report on), I have a python script that I use to wrap this api and do the right thing - available at https://github.com/Linaro/lkft-tools/blob/master/bin/generate_lts_report.py. Usage is e.g. 'generate_lts_report.py 4.19'. It should be straight forward to modify for your needs (and feel free to add it to that repo if you'd like).
Hope that helps, Dan