parameter 'to' contains an invalid email address 'undisclosed-recipients:'

Hi.
Z-Push 2.3.9 with zimbrabackend 67, I spotted these messages

13/03/2018 09:21:58 [13750] [WARN] [user] SyncObject->Check(): object from type SyncMail: parameter 'to' contains an invalid email address 'undisclosed-recipients:'. Address is removed.

actually many of them. Does it cause any harm/problem?
thanks

It is an email from a mailing list - The sanity check for valid email addresses in z-push causes it to get stripped.

You end up with a message that might have no To/Cc/Bcc address at all. Or is might just have no To address and still have a Cc or other address. It all depends on how the mailing list generates their addressing.

I have neveer seen any other side-effects

Ok it was just to know if it could be a problem. thanks