In Thunderbird, you can add multiple From email address for 1 account, and select it when composing a message (you can even set custom email address from composing window. Please try Thunderbird 68 or later) In Claws mail, you are tied to only one email address, which is defined in "Edit accounts" - "Account" - "Basic" - "Personal information" - "Mail address". Is there any way to achieve this? Typing alias email address each time is not an option.
*** This bug has been marked as a duplicate of bug 1606 ***