I´m trying to upload an email (I have the html code) to slack. I know that there is a possiblity to upload files using a slack email adress, but in my case I cannot use it.
I used the slack api method files.upload for this, but the files only appear as code lines and not as html content.
Yes, you can upload emails to Slack, but only as plain text files using files.upload. That however works pretty well.
To upload a plain text file with files.upload sent the file contents as string in content (this must be sent via a POST) and set filetype to text.