Add mail settings / send mailer

[qdraw]

PR Details

Description / Motivation and Context

Related Issue

How Has This Been Tested

• C# Unit tests
• Typescript Unit tests
• Other Unit tests
• Manual tests
• Automatic End2end tests (starsky-tools/end2end)

Types of changes

• Added for new features
• Breaking change fix or feature that would cause existing functionality to change
• Changed for non-breaking changes in existing functionality for example docs change / refactoring / dependency upgrades
• Deprecated for soon-to-be removed features
• Removed for now removed features
• Fixed for any bug fixes
• Security in case of vulnerabilities

Checklist

• My code follows the code style of this project.
• I have updated the documentation accordingly (update when needed)
• I have read the CONTRIBUTING document.
• I have added tests to cover my changes.
• All new and existing tests passed.
• I have updated the ./history.md document