Custom alias restoration problem

According to this source a CUSTOM DOMAIN ALIAS can be restored after deletion. So, after a test I discovered that emails sent from other email addresses are received by the restored alias, but it seems that password reset emails sent from different sites are never received. What is the problem?
It seems that even the site/service account is deleted and recreated with the same alias (which was previously deleted and restored) no email is received from site/service.

Is there any possibility that the site/service places the respective alias for which it received the message (“552 5.2.2 : Recipient address rejected: Address does not exist”) in a block list??? If so, are these block lists maintained forever, or do they have an expiration date?

PS: I know that aliases can also be just disabled, but deleting them allows better/easier management of them.