Skip to main content
In February 2024, Google and Yahoo began enforcing stricter requirements for bulk email senders. If you send 5,000 or more messages per day to Gmail or Yahoo addresses, you must comply with these rules or face delivery failures, spam filtering, and eventual blocking. These requirements apply to all senders — not just marketers. Transactional email senders with high volume are equally affected.

​
Who Is Affected

The bulk sender threshold is 5,000 messages per day to Gmail or Yahoo recipients. This is measured per sending domain, not per account or IP address. Even if you don’t currently send at that volume, following these requirements is good practice. Google and Yahoo have stated they may lower the threshold over time, and the requirements align with industry best practices that benefit all senders.
Some requirements (like email authentication) apply to all senders, not just those above the 5,000/day threshold. Only the one-click unsubscribe requirement is specific to bulk senders.

​
The Three Pillars

1

Authenticate your email

SPF, DKIM, and DMARC must all pass for your sending domain. This is no longer optional — it is a hard requirement.
2

Enable easy unsubscribe

Marketing and promotional emails must support one-click unsubscribe via the List-Unsubscribe header. Unsubscribe requests must be processed within 2 days.
3

Keep spam complaints below threshold

Your spam complaint rate must stay below 0.3%. The target is below 0.1%. Consistently exceeding 0.3% will result in blocking.

​
Authentication Requirements

All three authentication protocols must pass for your sending domain:
All three are required — passing just one or two is not sufficient. DMARC alignment means the domain in the From header must match (or be a subdomain of) the SPF or DKIM domain.

​
Verifying Your Authentication

Check your DKIM record:
Check your DMARC record:
You should see output similar to:
If either command returns no results, the record is missing and needs to be added.

​
Unsubscribe Requirements

For bulk senders, Google and Yahoo require:

​
Implementation in Lettr

Add the data-msys-unsubscribe="1" attribute to your unsubscribe link to enable unsubscribe event tracking and proper header generation:
Click tracking must be enabled for the data-msys-unsubscribe attribute to generate unsubscribe events. Lettr will automatically add the appropriate List-Unsubscribe and List-Unsubscribe-Post headers when this attribute is present.

​
Transactional Email Exception

One-click unsubscribe is only required for marketing and promotional emails. Purely transactional emails (order confirmations, password resets, account alerts) are exempt. However, if your transactional email contains promotional content, it may be classified as commercial and the requirement applies.

​
Spam Rate Requirements

Google measures your spam complaint rate through Gmail’s feedback mechanisms. You can monitor this through Google Postmaster Tools.

​
Monitoring with Google Postmaster Tools

  1. Go to Google Postmaster Tools
  2. Add and verify your sending domain
  3. Monitor the Spam Rate dashboard regularly
  4. Set up alerts if your rate approaches 0.1%

​
Reducing Spam Complaints

  • Make unsubscribe easy — A visible, one-click unsubscribe is the most effective way to reduce complaints. Recipients who can’t find the unsubscribe link will use the spam button instead.
  • Send relevant content — Segment your audience and send content they expect to receive.
  • Honor frequency expectations — Don’t email more often than subscribers signed up for.
  • Clean your lists — Remove unengaged subscribers who haven’t opened or clicked in 6+ months. See List Hygiene.
  • Use double opt-in — Confirm subscriptions to ensure recipients genuinely want your emails.

​
Additional Requirements

Google and Yahoo also require:
Most of these infrastructure requirements are handled by Lettr automatically. Your primary responsibilities are domain authentication (DKIM + DMARC), unsubscribe implementation, and maintaining a low spam complaint rate.

​
Compliance Checklist for Lettr Users

1

Verify your domain in Lettr

Add your sending domain and configure the CNAME and DKIM DNS records. Confirm both show as valid in the dashboard.
2

Add a DMARC record

Add a TXT record for _dmarc.yourdomain.com with at least v=DMARC1; p=none; rua=mailto:dmarc@yourdomain.com. See DMARC for details.
3

Set up a tracking domain

Configure a custom tracking domain (e.g., track.yourdomain.com) to improve link reputation. See Tracking Domains.
4

Implement unsubscribe links

Add data-msys-unsubscribe="1" to the unsubscribe link in your email templates. Ensure the link is visible and functional.
5

Register with Google Postmaster Tools

Add your domain at postmaster.google.com and verify ownership to start monitoring spam rates and reputation.
6

Monitor your spam complaint rate

Check Postmaster Tools regularly. If your rate approaches 0.1%, take immediate action to reduce complaints.

​
What Happens If You Don’t Comply

Gmail and Yahoo will outright reject emails from senders who fail authentication checks. You’ll see 550 5.7.26 or similar errors indicating DMARC or DKIM failure. These rejections appear as hard bounces in Lettr.
Even if emails are accepted, they may be automatically placed in the spam folder if your spam complaint rate is too high or your authentication is incomplete.
Gmail may temporarily throttle your sending if you’re borderline on compliance. You’ll see increased email.deferred events as Gmail slows acceptance of your messages.
Persistent non-compliance — especially a consistently high spam complaint rate above 0.3% — can result in your domain being permanently blocked by Gmail or Yahoo. Recovery requires fixing the root cause, reducing volume, and gradually rebuilding reputation.

Unsubscribe Best Practices

Implement effective unsubscribe mechanisms

SPF, DKIM, and DMARC

Understand email authentication protocols

DMARC Setup

Configure DMARC for your domain

Emails Landing in Spam

Troubleshoot spam folder placement