Hey @sergio-tjong
the Appdrag email forward are working and you should still receive your emails
but indeed, Google decided to deprecate sending mail from Less secure SMTP account (this is what you have if you followed our tutorial
Solution: you have to edit in GMAIL your alias and set a new SMTP configuration to be able to send emails from that alias
Since Google is not providing anymore the free SMTP service, you will need to use a third party SMTP service.
I can recommend MXRoute (https://mxroute.com/)
Nice because they provide unlimited domains & mailbox for a flat annual fee ($45/year)
or Zoho (https://www.zoho.com/mail/zohomail-pricing.html)
$1/month per mailbox