Certification envelope
An envelope used in administering absentee voting. Identifiable information about the voter is written on the outside of the envelope. A secrecy envelope containing a ballot is sealed inside the certification envelope. The certification envelope is used to ensure that the voter votes, and the ballot is counted, in the correct jurisdiction. Used as part of the double-envelope process.
Source: Independent Panel on Internet Voting, British Columbia, https://elections.bc.ca/docs/recommendations-report.pdf