In addition to my personal Gmail account, I have a number of G-Suite professional accounts. I have been forwarding all of those to my Gmail account, and have set up multiple "Send mail as" identities to send mail via the various professional accounts from the same place.
Now one of the G-Suite admins has closed off the "Less secure apps" option on their side, causing my "Send mail as" setup to fail with the error:
Server returned error: "534-5.7.9 Application-specific password required. Learn more at 534 5.7.9 https://support.google.com/mail/?p=InvalidSecondFactor w9sm914982ejn.54 - gsmtp , code: 534"
I've tried using an App Password instead (along with 2FA enabled), but I still get the same error. What can I do to keep using my Gmail account as gateway to the other accounts?
