Mailable Blank Subject

[temp1029]

• Laravel Version: 7.30.4 (but also exists in v8)
• PHP Version: 7.4.24

Description:

Cannot set mailable subject line to nothing.

Steps To Reproduce:

Create new mailable.
Set subject line to an empty string, null or false (all of which would indicate no subject line is desired).
Send mailable.
Subject line is set to the name of the mailable child class.

Further Details:

The problem occurs with the 'buildSubject' method on the 'Mailable' class. This method, helpfully, tries to ensure a subject line by checking if the subject property is 'truthy'. Unfortunately there are cases where a subject line may not be desirable, such as when using a provider which allows the sending of templates (and overriding the template subject line is also allowed).

A simple, additional, check that the subject property is not set to false (I think false is best but some other value might work too) would do it, just so users have the option to send an empty subject line.