TYPO3 EXT:powermail prefill or preselect a field via url

Yes it is possible. See documentation of powermail: https://docs.typo3.org/typo3cms/extensions/powermail/ForAdministrators/BestPractice/PrefillField/Index.html

The standard way

Prefilling (input, textarea, hidden) or preselecting (select, check, radio) of fields will be done by the PrefillFieldViewHelper. It listen to the following methods and parameters (in this ordering):

1. GET/POST param like &tx_powermail_pi1[field][marker]=value
2. GET/POST param like &tx_powermail_pi1[marker]=value
3. GET/POST param like &tx_powermail_pi1[field][123]=value
4. GET/POST param like &tx_powermail_pi1[uid123]=value
5. If field should be filled with values from FE_User (see field configuration)
6. If field should be prefilled from static Setting (see field configuration)

7. Fill with TypoScript cObject like

   plugin.tx_powermail.settings.setup.prefill {
       # Fill field with marker {email}
       email = TEXT
       email.value = [email protected]
   }
   

8. Fill with simple TypoScript like

   plugin.tx_powermail.settings.setup.prefill {
       # Fill field with marker {email}
       email = [email protected]
   }
   

9. Fill with your own PHP with a Signal. Look at In2codePowermailViewHelpersMiscPrefillFieldViewHelper::render()