"Invalid attachment" error

[SP]

Hello,

I am a relative newbie, using GYB to Backup and Restore two G-Suite accounts to private Gmail account.

I moved the first account with no issues.

The second account is large, 12+ GB. The Backup went fine. The Restore generated this error:

ERROR: 400: Invalid attachment. Please check https://support.google.com/mail/answer/6590.. Skipping message restore.

The final result was 12,118 of 12, 967 messages restored. 

1. How can I find out which messages were not restored?

2. What should I do at this point?

Thank you for any help.

[SP]

Hello,

It turns out that the "missing" messages were indeed restored, and had been put into Spam. I am leaving my post here in case it helps someone else. I still don't know which message(s) generated the 400 Error and failed, but I am confident they were probably true spam.