Electronic communication procedures: designated official emails and PDF attachments govern secure service, response, archiving, and audit trails. Procedure mandates that the AO send statutory notices and orders from a departmental designation email with signed PDF attachments to the assessee's primary email (as per returns, company records, or furnished to the AO), while the assessee must reply from that primary email with supporting documents in PDF, follow specified subject line and pagination formats, forward any email error messages to the departmental audit mailbox, and ensure all communications are archived in the Department database and reflected on the e filing account.