I am using catchall email adresses with my own domain.
For several purposes I have several adresses, p.ex. firstname.lastname@example.org, email@example.com, firstname.lastname@example.org etc.
With thunderbird on Desktop, there is no issue. It chooses automatically the email adress the mail was sent to (p.ex. email@example.com) and uses it as the sender email.
Example: So if firstname.lastname@example.org sends me an email to email@example.com and I want to answer, thunderbird will send the email from firstname.lastname@example.org. I never added email@example.com as a separate email account in thunderbird, I only set up firstname.lastname@example.org.
The sender email email@example.com is automatically created as a sender address once a mail to a address abc(or whatever)@mydomain.com is received
I am now looking for an email client on android doing the same.