errors get logged in your @runtime/logs/app.log also if you would like to debug your email you can log your emails to file using the file transport here is a example config by default it will save your messages to @runtime/mail directory.
I have read this article,of course. I need informations in this log for my database.
For instance, I have attribute in my table being filled in what kind of mailing error had occured while sending.
So, it will be more complicated,as I thought, won’t it? I have to investigate file in frontend/runtime/mail respectively frontend/runtime/logs. That’s a lot of effort for one single attribute