Client not respecting JSON serialization options
Well, since the code looks like it's ASP.NET conform, the client isn't at all. As mentioned in https://github.com/ActiveCampaign/postmark-dotnet/issues/117 already, there are significant flaws.
One more is that the client totally ignores any configured serialization options when using templated messages. There is simply no way to influence how the model is serialized since you can only pass the TemplatedPostmarkMessage object but have no way to pass the JSON options of your service. The service is DI-injected but does not consider the JsonOptions ASP.NET exposes via DI.
This is a serious issue. Since the repository is also stale, looks like the community gotta build their own solutions now I guess.
We will work around that by converting our ObjectIds into strings, but that kind of beats the purpose of having model classes... When we find time we probably gonna ditch the client and write our own then, if the client doesn't get any updates (stale PRs for years, great).
Hope this changes, it's really a bummer that so many paid tools don't maintain their own libraries.