No. PCI DSS Requirement 4 prohibits the sending of unprotected primary account numbers (PANs) via end-user messaging technologies, whether sent internally or over public networks. E-mail, instant messaging, SMS, and chat are all considered end-user messaging technologies and thus required to meet PCI DSS Requirement 4. Per PCI DSS Requirement 4, strong cryptography and security protocols must be used when cardholder data is sent over open, public networks.

For guidance on what to do if PAN is inadvertently received via an end-user messaging channel, refer to FAQ #1157 - What should a merchant do if cardholder data is accidentally received via an unintended channel?

Note: The specific sub requirement number(s) and terminology may vary depending on the version of the standard being used.