Powermail is a well-known, editor-friendly, powerful and easy to use mailform extension with a lots of features (spam prevention, marketing information, optin, ajax submit, diagram analysis, etc...)

Please look at the manual for a big documentation at https://docs.typo3.org/typo3cms/extensions/powermail

Quick guide:

• Just install this extension - e.g. composer require in2code/powermail or download it or install it with the classic way (Extension Manager)
• Clear caches
• Add a new form (with one or more pages and with some fields to a page or a folder)
• Add a new pagecontent with type "powermail" and choose the former saved form
• That's it

Please look at https://docs.typo3.org/typo3cms/extensions/powermail/Changelog/Index.html

• Automatically convert emails to a link to a powermail form with email2powermail (see https://github.com/einpraegsam/email2powermail)
• Google recaptcha with powermailrecaptcha (see https://github.com/einpraegsam/powermailrecaptcha)
• Google invisible recaptcha with invisiblerecaptcha (see https://github.com/einpraegsam/invisiblerecaptcha)
• powermailextended is just an example extension how to extend powermail with new fields or use signals (see https://github.com/einpraegsam/powermailextended)

• General update for TYPO3 7.6 and 8.x
• Table name correction from plural to singular (..mails => ..mail, ..fields => ..field)
  • Updated ext_tables.sql
  • Converter script to convert old tablenames to new tablenames
    • Automaticly on extension installation
    • Start manually from extension manager
• Add bootstrap
  • Frontend
    • Add static template to add bootstrap classes to forms and fields
    • Add constant to load bootstrap.css from powermail folder
    • Update Layouts, Templates, Partials (Pi1 and Pi2)
  • Backend
    • Update modules with new markup
• Backend
  • PluginInformation refactoring
  • Remove old form converter (converted 1.x to 2.x forms)
  • Remove unneeded overview actions
  • Enable table garbage collector scheduler tasks per default
• General
  • Add DataProcessors to change mail object before it's persisted or used in mails
  • Own spamshield methods could be registered via TypoScript now
  • Refactoring of upload function
  • Add signals to ValidationDataAttributeViewHelper, PrefillFieldViewHelper and PrefillMultiFieldViewHelper
  • Remove outdated parts of code (PHP, Templates)
  • Some code cleanup
  • Manual update