Skeleton Deliver: Unsupported sendmail flags

Note: Split off by @pamtbaau as separate question
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I could not install the skeleton on the local Open Server.
It gave me an error:

I had to configure the email plugin and everything worked.
The solutions described elsewhere have not helped.

p.s. The fixes in the .yaml files were not useful, maybe someone will find it useful.

@RobotWerter, This issue is unrelated to your original post. Burying different issues in a single post is not a good practice. The subsequent issue will be hard to find, does not match the title and cannot be marked as 'solved'.

Please open a new post with a proper title and body. Then add a reply with the solution of the issue. That reply can then be marked as 'solution'.

I'm sorry, maybe I'm just a little short-tempered.
Maybe I didn't describe the essence in the first post. Another user's post showed that the skeleton works. I used a search engine to find similar problems. The links I found suggested to solve the problem by editing .yaml files
For the local server I am using this did not solve the problem. Eventually I was able to figure out and get the skeleton running.
Replicating threads on the forum isn't quite right, but if you feel that way, maybe that's the best solution.
But I'm used to everything having to run smoothly. Gravity set up easily, but the skeleton gave an error. Developers of Open Server may be with crooked hands, but I've been using their product for a long time and all CMS worked without errors. I like Gravity, but this CMS is not for blondes)))))