Sending encrypted/password protected attachments via ZeptoMail?

Sending encrypted/password protected attachments via ZeptoMail?

Hi, I'm trying to send password protected PDF files via ZeptoMail but I'm getting the following error: 552 5.7.1 virus Heuristics.Encrypted.PDF detected by Zoho Mail.

Is there a way to bypass that error? Or, are there specific types of encryption allowed/disallowed by ZeptoMail/Zoho Mail?