Fix #1804: remove <!doctype html> and accept invalid HTML #1851
Add this suggestion to a batch that can be applied as a single commit.
This suggestion is invalid because no changes were made to the code.
Suggestions cannot be applied while the pull request is closed.
Suggestions cannot be applied while viewing a subset of changes.
Only one suggestion per line can be applied in a batch.
Add this suggestion to a batch that can be applied as a single commit.
Applying suggestions on deleted lines is not supported.
You must change the existing code in this line in order to create a valid suggestion.
Outdated suggestions cannot be applied.
This suggestion has been applied or marked resolved.
Suggestions cannot be applied from pending reviews.
Suggestions cannot be applied on multi-line comments.
Suggestions cannot be applied while the pull request is queued to merge.
Suggestion cannot be applied right now. Please check back later.
This fixes #1804 in two ways: First, it removes a <!doctype html> from
the start of the mail, if there is any.
Then, it parses the html itself it quick-xml fails, just stripping
everything between < and >.
Both of these would have fixed this specific issue, but they are probably both useful for similar issues.
Also, add tests for both fixes.