By vs Until in Work Emails: Deadlines and Duration

Use by for the latest time a result is needed, and until for how long an activity or state continues. “Send the list by 2 p.m.” asks for a completed delivery. “Keep the list current until noon” asks for continuing work up to a stopping point.

The choice depends on the whole sentence and the work you mean. This lesson lets you practice the difference in a short email, then change the message when a different task is needed. All names and workplace details below are fictional.

Match the time phrase to the task

In its time-related sense, by sets an upper limit: the result is needed at or before that time. This is the meaning described in Oxford’s entry for by.

Until identifies the point up to which something continues. Oxford’s entry for until explains this time or event boundary.

What you mean	Example wording	What the reader should understand
A result is needed no later than a time	Could you send the list by 2 p.m.?	Complete the delivery at or before the limit
A state continues up to a time	Registration remains open until noon.	Noon is the closing time
Work should continue up to a time	Could you keep the list current until noon?	Continue updating it during that period

These patterns help with the positive requests and statements in this lesson. They are not a rule that one particular verb always needs the same preposition.

Why “have until” can also describe a deadline

This sentence is natural:

You have until 3 p.m. to review the draft.

It describes the time available for completing the review. It does not require the reviewer to continue working for the whole period if the review is finished earlier.

Compare that with “Keep reviewing the draft until 3 p.m.” That asks for an activity to continue. The construction changes the meaning; replacing one word is not enough. Simple English Videos’ by-and-until lesson also illustrates how both words can be used when discussing deadlines.

Practice: request one final list

You are Alina, coordinating an internal workshop. Ben handles the registration information and already has access to the registration form and shared attendee list.

Use these facts:

• Registration is open now and closes at noon London time on 4 December 2026.
• You need Ben to email you one final attendee list after registration closes, no later than 2 p.m. London time that day.
• You are making this request; Ben has not yet accepted it.
• No file is attached to your request. The workshop date and number of attendees have not been supplied.

Before reading the example, write a subject and a short email. Explain how long registration stays open, then ask for the final list. Keep the closing time separate from the requested delivery time.

One possible email

Subject: Final workshop attendee list — requested by 2 p.m. on 4 December

Hi Ben,

Registration for the internal workshop remains open until noon London time on 4 December 2026.

After registration closes, could you email me the final attendee list by 2 p.m. London time that day?

Thanks, Alina

“Until noon” describes the form’s open period. “By 2 p.m.” gives Ben the latest requested delivery time. “After registration closes” adds a separate condition: the list should reflect the completed registration period.

The message asks Ben to send one final list. It does not ask for repeated emails throughout the afternoon, and it does not present the requested deadline as something Ben has already agreed to.

Check the meaning

Consider these two questions before looking at the answers:

1. Ben emails the completed list at 1 p.m., after registration has closed. Does that meet the requested timing?
2. Does the noon closing time mean the final list must be emailed at noon?

Answers: Yes to the first: 1 p.m. is after closure and before the 2 p.m. limit. No to the second: noon is the form’s closing time, while 2 p.m. is the requested delivery deadline. These answers follow the facts supplied for this task.

Revise it: keep a shared list current instead

Now change the task before sending your email. The team will use the live shared attendee list instead of receiving a final file. You need Ben to keep that list up to date as registrations arrive, until the form closes at noon London time on 4 December 2026.

There is now no separate emailed final list and no 2 p.m. delivery requirement. Ben’s access and the closing time are unchanged.

Rewrite your message before reading the next example. Change the action as well as the time phrase, and remove the request that no longer applies.

One possible revised email

Subject: Workshop registrations — keep the shared attendee list current

Hi Ben,

The team will use the shared attendee list for the internal workshop. Could you keep it up to date as registrations arrive, until the form closes at noon London time on 4 December 2026?

There’s no need to email a separate final list.

Thanks, Alina

This version asks for continuing updates during registration. “Keep it up to date” identifies the activity, and “until the form closes” states when it ends.

Simply changing “send the list by 2 p.m.” to “send the list until noon” would not explain that new task. The revised email names the shared list and the ongoing work. It also removes the old delivery request and the obsolete 2 p.m. time.

Compare both of your drafts. Can Ben tell whether you want one completed delivery or a list kept current over a period? The message should answer that question without requiring him to guess from the preposition alone.

Check the action before checking the preposition

When you edit a work email, identify the result or continuing activity first. Then check that the time phrase matches it. If the work changes, review the whole request for an old action or deadline that should disappear.

For clear dates and other wording choices, read business email English for non-native speakers. If an existing deadline needs to change, practice requesting a deadline extension. For more tasks to attempt before comparing examples, use the professional email writing exercises.

To practice your own wording, start practicing for free. EmailBetter sends workplace scenarios tailored to your profile to your inbox. You write your reply in your usual email app, then review AI feedback in your dashboard.