Step 1: Enable Third-Party Mail Clients

Google may block (by default) third-party (less secure) mail clients like e.g. Outlook, Thunderbird, MailList Controller or Inbox2DB.

See: https://support.google.com/accounts/answer/6010255?hl=en for details.

The page contains a link to enable "Less secure apps" in MyAccount.
You can also enable "Less secure apps" (third-party mail clients) from:
"MyAccount" > "Sign-in & security" > "Connected apps & sites" > "Allow less secure apps"

Step 2: Gmail SMTP Server
Enter the following information in the SMTP account settings of your mail client:

Server: smtp.gmail.com
Encryption/Authentication: SSL
Port: 465

or

Server: smtp.gmail.com
Encryption/Authentication: StartTLS
Port: 587

step3: Change From address

1. On your computer, open Gmail.
2. In the top right, click Settings.
3. Click the Accounts and import or Accounts tab.
4. In the "Send mail as" section, click Add another email address.
5. Enter your name and the address you want to send from.
6. Click Next Step and then Send verification.

Read More:

• https://www.arclab.com/en/kb/email/how-to-enable-imap-pop3-smtp-gmail-account.html 
• https://stackoverflow.com/questions/1332510/how-to-change-from-address-when-using-gmail-smtp-server
• https://github.com/PHPMailer/PHPMailer/wiki/Troubleshooting