Take a tip from a postal worker: always place your complete return address on everything you mail. Without that information, if delivery can’t be made, undelivered mail goes to the Dead Letter Department where specialists attempt to find an address.
If you are mailing packages, include the delivery information on a separate sheet inside for both sender and recipient addresses. Packages routinely get crushed or punctured from multiple handling during processing.
Don’t ever put solid objects in paper envelopes. The contents will be crushed by automated machines and the envelope will be in shreds. Always use “Jiffy” type padded envelopes for solid objects.
Use good quality envelopes for your Christmas cards. Those $1 store envelopes are too thin and won’t stand up to the postal machinery.
If your envelope says “extra postage required” it means just that. Put an extra 44c stamp on it.
Mail early for all on your Christmas card list. Mail volume is picking up already.