Every address

Minutes to weeks

A number and a letter. These return exactly that long after they are sent, and are the only addresses that arrive at a time of day of your choosing rather than in the morning.

These are measured as elapsed time rather than as calendar dates. A three-day request returns three days later at the same time of day, not on the morning of the third.

Months and years

For matters that genuinely belong a year away: a warranty, a renewal, a commitment to follow up. These hold the date and the time of day, and move the calendar.

Shorter months are handled predictably. Sent on 31 January, 1mo@ returns on 28 February. Sent on 29 February, 1y@ returns on the 28th.

Tomorrow, and reminders that repeat

These arrive at 6:30 in the morning, in your account’s timezone.

Repeating reminders never fire on the morning they are created. A message to weekly@ at half past seven on a Tuesday first arrives the following Tuesday, since a weekly reminder delivered thirty minutes after the request is not what was intended.

Days of the week

These arrive at 6:30 in the morning too — every address that does not name an hour of its own arrives then.

Every day works in both forms, as does each common abbreviation:

Each spelling accepts the each- prefix, so each-weds@ is as valid as each-wednesday@.

As above, these never fire on the same morning. A message to friday@ at six on a Friday returns the following Friday rather than thirty minutes later.

Months

A month name is the 1st of that month, at 6:30 in the morning. If the 1st has already gone this year, it is the 1st of next year.

Every month works in full or short, and takes the each- prefix:

A time of day

An address can name an hour outright, and then it arrives at that hour rather than at 6:30. 12am@ is midnight and 12pm@ is noon.

Every hour works: 1am@ through 11am@, 12pm@, 1pm@ through 11pm@, and 12am@. As with every other schedule, one never fires within the hour it was asked for — 5am@ sent at twenty to five returns the following morning, and 12am@ sent at half past eleven at night waits for the midnight after next.

Cancelling a series

Every repeating reminder arrives with a line at the foot explaining how to stop it. Forward that message to cancel@mailwhen.com and the series ends.

The reminder itself must be the message you forward, as it carries the code identifying which series to end.

What is pending

Send an empty message to list@mailwhen.com and it replies with everything still scheduled: when each one arrives in your own timezone, the address that set it, and the subject it came from. A repeating reminder is marked as such and shows its next arrival rather than its last.

If anything is pending, the subject of the reply says how many and the day the next one arrives, so you can see that a reminder is still coming without opening anything. A message with a subject of its own is answered under that subject instead.

It is a question rather than a request, so it creates no reminder and counts against no limit.

Starting an account

Send anything to register@mailwhen.com and it replies asking you to confirm. Confirming is a plain reply with nothing typed: the address it replies to is what confirms it.

Any reminder address does the same, so you do not have to know this one. Mail 3d@mailwhen.com without an account and you get the same confirmation — that first message is not turned into a reminder, so send it again once you are confirmed.

If no confirmation arrives within a few minutes, look for a message from register@mailwhen.com in your junk or quarantine folder. Some mail systems hold it there, and at work only an administrator may be able to release it. MailWhen also stays silent, rather than guess, when it cannot verify that a message came from the address it claims to. If you cannot find the confirmation, write to hello@mailwhen.com and a person will set the account up. The confirmation itself is good for 3 days; if it lapses, the same address gets it started again.

Being copied, and stopping

If somebody puts a MailWhen address in To or Cc alongside you, and you have a MailWhen account of your own, the reminder reaches you as well. Would rather it did not? Mail stop@mailwhen.com and you will not be copied on anyone's reminders again.

It takes effect immediately and for good, across every sender, and it needs no account. Reminders you set for yourself are unaffected.

Practical notes

To, CC and BCC all work

BCC is the most useful of the three: it lets you set a reminder on a message you are sending to someone else, entirely invisibly.

Several addresses at once

Include 1d@ and 1w@ on the same message and you receive two reminders, one at each time. Each address is a separate request.

Who else is reminded

Where you put the address decides it. Bcc it and the reminder returns to you alone — the other recipients receive nothing and are never informed a reminder exists. Put it in To or Cc, where they can all see it, and each of them who also uses MailWhen is reminded alongside you. Anyone who does not is left out, and you are told who.

Duplicate messages are recognised

Email is routinely retried in transit. If your provider hands MailWhen the same message twice — which you would never see — it is recognised as the same message and you get one reminder.

Forwarding something again yourself is a new message, and gives you a second reminder. That is usually what you meant by forwarding it again.

An incorrect address is harmless

You will receive a short note naming what was not understood, along with the addresses that are valid. Nothing is lost, and any valid address on the same message is still scheduled.

Delivery times

Two rules cover everything:

• Minutes, hours, days and weeks return exactly that long after they are sent, whatever the hour.
• An address naming an hour — 5am@, 9pm@ — returns at that hour.
• Everything else returns at 6:30 in the morning: tomorrow@, weekly@, monthly@, a named day, and a month.

Daylight-saving transitions are handled correctly. A morning reminder remains a morning reminder on both sides of one. On the two days a year the clocks move, an hour that happens twice or does not happen at all resolves to the earlier of the two instants — so a reminder can arrive an hour early, but never an hour late.

Your timezone

Each account has its own, and it is what every arrival time above is measured in. An account you set up yourself starts on US Central time.

To change it, send an empty message to an address naming your zone. tz- and the standard name of the timezone, in lower case, with the slash and any underscore written as a dash:

Every standard timezone name works the same way, so tz-pacific-auckland@ and tz-africa-nairobi@ are real addresses without being listed here. So are the older regional spellings — tz-us-eastern@, tz-canada-pacific@ — because those name a place too. MailWhen replies to say which zone you are on.

Reminders you create afterwards follow the new zone. Anything already scheduled keeps the time it was set for, and the reply lists those with their arrival times in your new zone, so you can see which ones to set again.