There are also prohibitions and restrictions around other items not mentioned in previous sections of this article.

• Unsealed envelopes and unsealed self-mailers are unacceptable for mailing when deposited as Letter-post 
• Envelopes (except Special Handling) with windows are unacceptable for mailing unless the:
  • Window has a transparent cover parallel to the length of the envelope
  • Address of the addressee is easily read
  • Address doesn’t interfere with the date-stamping process
• When mailed at the Incentive Lettermail™ price, we only allow one auxiliary window on the front or the back of an envelope
• Items in wholly transparent envelopes are unacceptable for mailing unless:
  • They can be easily handled by post
  • The outside label is securely attached and is large enough for the name, address, postage, and any applicable service instructions

• With certain exceptions, items that have anything written, printed, or attached on their outside cover are unacceptable for mailing. Exceptions include:
  • The name and address of the addressee or the sender
  • Endorsements or attachments which we authorize or which are otherwise authorized by statute or regulation
• Items with covers that bear words, devices, and so on which may adversely affect the commercial or social standing of the addressee are unacceptable for mailing.
• Items with covers that bear rings or similar advertising devices appearing around the postage stamps are unacceptable for mailing. This includes hand-stamped or printed copies of postal cancelling or franking stamps.
• Items with covers that bear non-postal (private manufacture) stamps or stickers are unacceptable for mailing if they’re affixed in such a way that they may be mistaken for postage stamps or postal franking impressions, or otherwise indicate value.

• Mail is unacceptable for mailing if it bears successive addresses.

• Pre-printed labels and endorsements must:
  • In no way imply, through pre-printed terminology or graphics on the mail piece, special handling or a service for which you haven’t paid postage
  • Not duplicate trade-marks of, or used under licence by Canada Post
  • Be directed to the addressee as an instruction related to the enclosure
  • Be cleared with us before printing to ensure the “mailability” of an item

• Any item emitting an offensive odour is unacceptable for mailing

• Precious metals are unacceptable for mailing, unless mailed under a written Agreement between the Mailer and Canada Post.

• These metals include:

  • Gold bullion
  • Gold dust
  • Non-manufactured precious metals

• Any other item is unacceptable for mailing if it contravenes:
  • The Universal Postal Convention
  • Any applicable law
  • Any other Canada Post requirements

Visit the Universal Postal Union Prohibitions Repository for information on dangerous products as defined by the International Air-Transport Association and as accepted by the Universal Postal Union.