How to Send Automatic Deadline Reminder Emails from Google Sheets

The spreadsheet had the date. Everyone knew the contract was up for renewal. Nobody got a deadline reminder email from Google Sheets, nobody sent one, and three weeks later the firm was paying an out-of-contract emergency rate.

This is not a rare story. It is one of the most common Google Sheets complaints in ops and admin communities: the data is there, the deadline is visible to anyone who opens the file, but there is no mechanism to surface it at the right time to the right person.

Here is how to fix that — three ways, with an honest comparison of each.

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What you are actually trying to do

The requirement is simple: when a date in column B is X days away, send an email to the address in column C. That is it.

The implementation options range from “clicks only, no code” to “write your own script.” Each has a different cost, flexibility ceiling, and failure mode. Choose based on what matters most to your team.

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Option 1 — Use a Google Workspace marketplace add-on

Two well-regarded add-ons handle this use case without any code:

Alerts & Notifications — Automate Google Sheets handles scheduled email alerts based on cell values and date conditions. You configure rules through a sidebar UI and the add-on manages the trigger schedule.

Tho Alert Sheet Notification takes a similar approach — rule-based alerts with a no-code configuration panel. It supports multiple recipients per alert and condition-based triggers.

Both install in under two minutes from the Google Workspace Marketplace.

When this is the right choice:

• You want something running in ten minutes
• Your organisation is comfortable installing third-party add-ons
• You do not mind a monthly subscription ($5–15/month depending on the tool and tier)

The trade-offs:

• Subscription cost adds up across multiple users or sheets
• You are dependent on the add-on staying maintained and priced reasonably
• Customising the email body or logic beyond the UI’s options is limited or impossible

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Option 2 — Write it yourself with Google Apps Script

Google Apps Script is free, already built into every Google Sheets file, and powerful enough to handle this in roughly 25 lines of code.

The core logic:

function sendDeadlineAlerts() {
  const sheet = SpreadsheetApp.getActiveSpreadsheet().getActiveSheet();
  const data = sheet.getDataRange().getValues();
  const today = new Date();
  today.setHours(0, 0, 0, 0);

  for (let i = 1; i < data.length; i++) {
    const deadline = new Date(data[i][0]);   // Column A: Deadline Date
    const email    = data[i][1];             // Column B: Recipient Email
    const subject  = data[i][2];             // Column C: Subject Line
    const daysBefore = data[i][3];           // Column D: Days Before Alert
    const status   = data[i][4];             // Column E: Status

    if (!deadline || !email || status === 'Sent') continue;

    deadline.setHours(0, 0, 0, 0);
    const daysUntil = Math.round((deadline - today) / (1000 * 60 * 60 * 24));

    if (daysUntil === Number(daysBefore)) {
      MailApp.sendEmail(email, subject,
        `Reminder: "${subject}" is due in ${daysBefore} day(s) (${deadline.toDateString()}).`
      );
      sheet.getRange(i + 1, 5).setValue('Sent');
    }
  }
}

To make it run daily: open Extensions → Apps Script → Triggers → Add trigger → choose sendDeadlineAlerts, time-driven, day timer.

When this is the right choice:

• You want full control over the email body and logic
• You are comfortable reading and editing simple JavaScript
• You want zero ongoing cost beyond Google Workspace

The trade-offs:

• You own the maintenance: if the script breaks (usually because of a column mismatch or trigger reset after a quota issue), you fix it
• No UI — edits require opening the script editor
• New team members need a handoff document to understand what it does

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Option 3 — Use a pre-built template (fastest path)

If you want the Apps Script approach but without writing or debugging the code, the Deadline Email Alerts Template gives you a pre-configured sheet with the script already included.

Setup:

1. Copy the template to your Google Drive (one click)
2. Fill in your deadlines — date, recipient, subject, days before
3. Run the setup function from the Extensions menu and set the daily trigger

Five minutes. The script handles duplicate-send prevention with a status column, supports any number of rows, and sends from your own Gmail account.

When this is the right choice:

• You want the Apps Script approach without writing any code
• You want a clean starting sheet structure rather than bolting a script onto an existing messy sheet
• You prefer a documented setup guide over figuring out triggers from scratch

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Side-by-side comparison

	Marketplace add-on	DIY Apps Script	Free template
Setup time	~10 min	~30–60 min	~5 min
Monthly cost	$5–15	Free	Free
Code required	None	Yes	None
Customisation ceiling	Limited by add-on UI	Unlimited	Moderate
Maintenance burden	Add-on manages	You manage	You manage
Per-row recipients	Varies by add-on	Yes (if coded)	Yes
Email sending account	Third-party or yours	Your Gmail	Your Gmail

The add-on is the simplest start if you are willing to pay. The DIY script is the right call if you want full control and have someone on the team who can maintain it. The template is the middle path: Apps Script power without the setup friction.

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When manual checking is still the right call

Automation is not always the answer for deadline tracking.

For high-stakes, low-frequency deadlines — a regulatory filing, a GDPR review, a lease agreement — a second human review is often worth more than speed. Automated alerts are easy to train yourself to ignore after a few weeks. A calendar invite with a named owner is harder to dismiss.

Use automated reminders for the long tail: contracts, certifications, subscriptions, and recurring tasks that happen frequently enough that manual tracking becomes the bottleneck. Keep the critical single-occurrence deadlines in a calendar, owned by a person, not a trigger.

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Ready to stop checking the sheet manually? Get the free Deadline Email Alerts Template →