fix: Shield may not send correct HTML mail

[kenjis]

Description Closes #1018, Resolves #1019

• fix emailer()
• fix code that sends email

Before:

After:

Checklist:

• [x] Securely signed commits
• [ ] Component(s) with PHPDoc blocks, only if necessary or adds value
• [ ] Unit testing, with >80% coverage
• [ ] User guide updated
• [x] Conforms to style guide