You can use the Security Investigation Tool to delete these messages from every users inbox. If you do not have G Suite Enterprise you can leveraging GAMADV-XTD Users-Gmail-Messages-Threads for this by issuing something like
gam all users delete messages query rfc822msgid:firstname.lastname@example.org doit
The best and most flexible way to do this may be to create a classic email list. Since you mentioned Gmail in your question, we can keep it in the Google ecosystem by creating our email list with Google Groups. Visit the Google Groups signup page and enter an email address for your email list (like email@example.com).
During sign-up, you should:
This is a 2016 Gmail feature. It indicates that Gmail can't confirm the sender's identity. In other words, Gmail is telling you that the email could be from a different sender than it says it's from.
Here is the Google support article on the feature.
Here is the original announcement.
You'll need to enabled "less secure" app access to your account.
First, go to your Google Account. On the left navigation panel, click Security. Near the bottom of the page, in the Less secure app access panel, click on "Turn on access (not recommended)":
This will bring you to a new screen with a control to click on to enable this access:
You can copy-and-paste/write you email on these websites convertcase.net or professionalediting.org and click "sentence case"
You don't have to install any extensions and it's accessible anywhere as long as you are online. It's a pretty lazy way to meet your purpose.
As I typed my question, I discovered the solution. Simply click on the "three dot" options button on the right of your email and click on "Show original". (It is like source code of your email.) Now search for "Delivered-To:" field and find the email address you were looking for.
I also had a similar problem with them and found although you own these addresses you would have to add them individually to be able to send a reply. I couldn't find no instructions to do this but I managed to figure it out by:
Logging in to Gmail via my desktop/computer
Click on settings (gear icon)
Accounts and imports setting
Scroll to section 'send ...