Further research shows this is a known issue. The solution (for me) was to remove the snap install of bluemail with:
pamac remove --no-save snapd
However, that does not remove all the bluemail files. The following command worked for me:
[quote="Mirdarthos, post:4, topic:164280"]
`sudo sh -c 'rm -rf /var/lib/snapd/cache/*'`
[/quote]
Then I installed bluemail from the AUR (which I should have done to begin with) and problem solved. 