False bounces when processing bounces

Using v3.4.6.
When processing bounces I have false (positive) bounce messages. They are all made unconfirmed by bounce rule 6.
How do I know?
It made my own e-mail address unconfirmed while I know for sure my mailbox is not over quota. Twice.

Could it be bounce rule 6 is confusing the to and from e-mail address?

You will need to show what bounce rule 6 actually is.

If the “bounce email” does not contain the headers of the original email then phplist has to guess which subscriber it applies to. In this case it looks for any email addresses in the email that are also subscribers. It sound possible that it finds the original From address and chooses that one. You will need to capture the contents of the bounce email to confirm this.

Bounce rule 6= RCPT TO:.* Mailbox disk quota exceeded

Auto Created from bounce 1185
line: Diagnostic-Code: smtp; 552 RCPT TO:xx@xx.com Mailbox disk quota exceeded

My mail address is indeed on the bouncelist of my last mailing campaign, but I did receive the mail in good order…