As mentioned in other issues (#1081, #1082) it is no longer possible to log in to Gmail via normal password.
One solution is to use app passwords but these require enabling 2-factor authentication.
Another one I found is to use Outlook.com as a IMAP-to-Gmail proxy. This requires any Office 365 license.
You don't need to open Outlook account, you can just sign in with any Microsoft account (including one created for *@gmail.com)
Once you do this, your Gmail account with show up as a folder named like your gmail login (including over IMAP)
Configure SMS Backup+ to use Outlook IMAP server - outlook.office365.com and your Microsoft account credentials
In backup settings update Gmail labels to be prefixed with the name of your account and /, e.g. you@gmail.com/SMS
That's it. It should work now. Outlook syncs emails back to Google with few minutes of delay so you may need to wait a bit for them to show up on Gmail side.
As mentioned in other issues (#1081, #1082) it is no longer possible to log in to Gmail via normal password. One solution is to use app passwords but these require enabling 2-factor authentication.
Another one I found is to use Outlook.com as a IMAP-to-Gmail proxy. This requires any Office 365 license.
you@gmail.com/SMS
That's it. It should work now. Outlook syncs emails back to Google with few minutes of delay so you may need to wait a bit for them to show up on Gmail side.