Just a patch to postal docker image ghcr.io/postalserver/postal:2.1.4 to add:
https://github.com/postalserver/postal/commit/f0a8aca6e10064fb16daefff9e22dcc20a831868
This fix is mentioned in this issue postalserver/postal#2153 (comment), however there is no release yet...
Published as ghcr.io/nicksellen/postal-fix:2.1.4-frozenstringpatch
To apply:
(run in directory where postal's docker-compose.yml is)
(and I trust you to take a backup of it or whatever...)
sed -i 's/ghcr\.io\/postalserver\/postal:2\.1\.4/ghcr.io\/nicksellen\/postal\-fix:2\.1\.4\-frozenstringpatch/g' docker-compose.yml