Start with the envelope, not the message

There is something quietly satisfying about a handwritten card landing on a doormat thousands of miles away. But before you get sentimental about the journey, remember that international mail is processed by machines and sorted by people who have never met you or your recipient. The address has to do all the work.

Write it in this order, working downwards: the recipient's full name, the house or building number and street, the town or city, the postal code, and finally the country. Put the country on its own line, in block capitals, and write it in English even if the rest of the address is in another language. If the destination uses a non-Latin script — Cyrillic, Arabic, Chinese, Greek — add the country name in that script too, so the last sorting office recognises it instantly.

A few specifics that catch people out:

• Omit the county. It means nothing to a sorter in another country and simply adds clutter.
• Never skip the postcode. Canada, the Netherlands, Ireland, the United States and most of Europe rely on theirs heavily; a missing code can add days.
• Write your own full address on the back of the envelope. If the card cannot be delivered, it comes home instead of vanishing.
• Use dark ink and clear capitals. Faint pencil or loopy cursive is an invitation to delay.

Customs declarations: a small label with big consequences

A card containing nothing but a handwritten message is, in most cases, just a letter. It travels without paperwork. The moment you tuck anything else inside — a photograph you printed yourself, a pressed flower, a tea bag, a bookmark, a tiny gift — it becomes goods, and the destination may expect a declaration.

Fill in the small green customs label honestly. Describe the contents plainly: one greetings card, one small wooden ornament, one packet of stickers. Mark it as a gift if it is one. Never write "present", "miscellaneous" or "personal items" and hope for the best; vague descriptions are the single most common reason a card sits in a customs queue for a fortnight.

Two things to avoid above all others. First, don't underdeclare the value, even gently — if the parcel is opened and the figures don't add up, your recipient may be the one answering awkward questions. Second, don't enclose cash, coins or a gift card. Many countries treat banknotes and cash-equivalent vouchers as prohibited in ordinary post, and they can be confiscated without compensation.

Also worth knowing: if the declared value crosses the destination's tax threshold, your friend may be asked to pay duty plus a handling fee before the card is released. A quick note warning them is a kindness.

Weight, shape and the things you cannot post

Standard international letter rates usually cover items up to about 100g, within set length, width and thickness limits. Embed a badge, a magnet, a wooden star or a string of beads in a handmade card and you have almost certainly exceeded the thickness limit, pushing it into large-letter or parcel pricing. Rigid, lumpy envelopes also jam sorting machinery, which is how cards arrive creased, torn or surcharged.

Weigh and measure before you seal anything. Then check the destination's own rules, because they can be stricter than ours. Common prohibitions include:

• Cash, coins, and gift cards or vouchers
• Loose lithium batteries, lighters and aerosols
• Perfume, alcohol and any liquid
• Seeds, plant material and soil
• Jewellery and other high-value small items

Confetti and glitter are legal but messy, and loose glitter can cause a card to be flagged for inspection. If the card is precious, use a board-backed envelope and accept that "please do not bend" is a request, not a guarantee.

How long it really takes

Postal services publish delivery aims, and they are broadly similar across providers. Treat these as working days, and don't count the day you post it.

• Western Europe: 3 to 7 working days
• North America: 5 to 12 working days
• Australia, New Zealand, Japan, Singapore: 7 to 14 working days
• Parts of Africa, South America and remote islands: 3 to 6 weeks

Add time for customs inspection, national holidays, extreme weather and industrial action at either end. Always send by air mail; surface mail is glacial where it still exists. A tracked service is rarely worth the cost for a card, but if you have tucked something valuable inside, compare the tracking fee against the value of the contents and decide sensibly.

Peak seasons punish late posting

December is not the month to be optimistic. For long-haul destinations, aim to post by mid-November. For Europe, the first week of December is a reasonable deadline; for UK-to-Ireland, a little later still works. Cards sent to another continent in the final week before Christmas will very likely arrive in January, which is fine if you have framed it as a New Year note.

And remember that celebration dates are not universal. Mothering Sunday in the UK falls in March, while Mother's Day in the United States is in May. Diwali, Eid, Lunar New Year, Easter and Hanukkah all move. Check the date before you write it inside.

Small habits of seasoned senders

• Weigh the finished card on kitchen scales before sealing it.
• Buy the correct postage for the right world zone; underpaid mail is returned or charged to the recipient.
• Photograph handmade or sentimental cards before they leave your hands.
• Keep a few spare customs labels in a drawer, along with a pen that works.
• Note down what you sent, to whom, and when — a simple list saves a great deal of head-scratching in February.

None of this takes more than a few extra minutes, and it is the difference between a card that arrives and a card that becomes a story about the one that never turned up. Do the small things properly, and the handwriting inside gets to do its proper work.