Message restore skips a lot of messages due to "Invalid label"

[wout-peeters-gs]

• I have upgraded to the latest GYB release from https://github.com/jay0lee/got-your-back/releases and I still have this issue.
• I am typing the command as described in the GAM Wiki at https://github.com/jay0lee/got-your-back/wiki

Full steps to reproduce the issue:

1. Backup a bunch of emails from a Gmail account
2. Restore said messages to other Gmail account

Expected outcome (what are you trying to do?): Messages restored

Actual outcome (what errors or bad behavior do you see instead?):
A large amount of errors like so:

ERROR: 400: Invalid label: IMPORTANT. Skipping message restore.
ERROR: 400: Invalid label: IMPORTANT. Skipping message restore.
ERROR: 400: Invalid label: SENT. Skipping message restore.
ERROR: 400: Invalid label: SENT. Skipping message restore.
ERROR: 400: Invalid label: IMPORTANT. Skipping message restore.

only a small number of messages is actually restored.

[wout-peeters-gs]

Seems that adding a prefix label with --label-prefix RESTORE worked around these errors.

[mtiraferri]

Same message, restoring mbox but stops the process.

Restoring from 22.69gb file c:\tmp\tb\recupero.mbox...
Creating label Da leggere
400: Invalid label name - invalidArgume