Gmail Email Sender Guidelines
Google's requirements for delivering to personal Gmail accounts — authentication, spam-rate thresholds, one-click unsubscribe, bulk-sender rules, and the enforcement timeline.
Google's Email Sender Guidelines define what any sender must do for mail to be accepted and delivered to personal Gmail accounts — addresses ending in @gmail.com or @googlemail.com. Requirements have been enforced since February 1, 2024 and grew stricter over time (see Enforcement timeline).
Scope notes:
- The guidelines and Google's enforcement apply only to mail sent to personal Gmail accounts. Messages sent to Google Workspace accounts are not covered by these guidelines — but all senders, including Google Workspace users, must meet them when sending to personal Gmail accounts.
- Google Workspace senders sending large volumes are additionally subject to the Gmail Spam and abuse policy.
See also: DMARC for SPF/DKIM/DMARC and alignment concepts, Yahoo sender requirements and Microsoft sender requirements for the parallel rules at other providers, and Google Postmaster Tools for the dashboards used to verify compliance.
Who counts as a bulk sender
"A bulk sender is any email sender that sends close to 5,000 messages or more to personal Gmail accounts within a 24-hour period."
Key mechanics:
- Counted per primary (organizational) domain, subdomains included. Google's example: 2,500 messages/day from
solarmora.complus 2,500/day frompromotions.solarmora.com= bulk sender, because all 5,000 came from the primary domainsolarmora.com. - Bulk sender status is permanent — "Bulk sender status doesn't have an expiration date." Dropping below 5,000/day later does not remove the status.
- Note the wording "close to 5,000": don't treat 4,999 as safe.
Requirements for ALL senders (any volume)
| Area | Requirement |
|---|---|
| Authentication | Set up SPF or DKIM for your sending domains |
| DNS | Valid forward and reverse DNS (PTR) records for sending IPs; the sending IP must match the IP of the hostname in its PTR record, and the forward lookup (A/AAAA) of that hostname must resolve back to the same IP |
| Transport | Use a TLS connection for transmitting email (no specific TLS version stated) |
| Spam rate | Keep user-reported spam rate in Postmaster Tools below 0.10%; never reach 0.30% or higher |
| Message format | Comply with RFC 5322 (Internet Message Format) |
| From header | Don't impersonate Gmail From: headers — Gmail applies a DMARC quarantine enforcement policy on gmail.com, so spoofing it will hurt delivery. Use a single email address in the From: field |
| Message-ID | Every message needs a valid Message-ID: header |
| Headers | Single-instance headers (From, To, Subject, Date) must appear exactly once; no duplicate or malformed headers |
| Content | No hidden content via HTML/CSS; web links must be visible and understandable; HTML must conform to standards; don't mix different content types (e.g., promotional receipt) in one message |
| Forwarding | If you regularly forward mail or run a forwarding service (mailing lists, gateways), follow Google's Best practices for forwarding email to Gmail — add ARC headers so Gmail can see the original authentication results, and keep the original authentication intact where possible |
Additional requirements for bulk senders (≈5,000+/day)
Everything above, plus:
| Area | Requirement |
|---|---|
| Authentication | Both SPF and DKIM (not either/or) |
| DMARC | Publish a DMARC record for the From: domain. Minimum policy p=none is acceptable |
| Alignment | For direct mail, the From: header domain must be aligned with the SPF domain or the DKIM domain (organizational-domain / relaxed alignment suffices) |
| DKIM key | Minimum 1024-bit key; 2048-bit recommended |
| One-click unsubscribe | Marketing and subscribed (promotional/commercial) messages must support RFC 8058 one-click unsubscribe via both headers:List-Unsubscribe: <https://example.com/unsubscribe/…>List-Unsubscribe-Post: List-Unsubscribe=One-Click |
| Visible unsubscribe | A clearly visible unsubscribe link in the message body as well |
| Honor unsubscribes | Process unsubscribe requests within 48 hours |
One-click unsubscribe specifics (from Google's FAQ):
- Required only for marketing/promotional messages; transactional messages are excluded.
- A
mailto:List-Unsubscribealone does not satisfy the requirement — RFC 8058 requires the HTTPS POST mechanism. - Additional unsubscribe links in the message body don't have to be one-click.
- One-click unsubscribe may remove the recipient only from that specific mailing list, not necessarily all communication from the sender.
Enforcement timeline
| Date | What changed |
|---|---|
| February 1, 2024 | Requirements take effect for senders to personal Gmail accounts; bulk senders (5,000+/day) must authenticate (SPF+DKIM+DMARC), avoid unwanted mail, and make unsubscribing easy. Enforcement began "gradual and progressive" — first temporary errors on a portion of non-compliant traffic, then increasing rejection rates |
| June 1, 2024 | Deadline for senders that already include an unsubscribe link to implement one-click unsubscribe in all commercial/promotional messages |
| June 2024 | Bulk senders with user-reported spam rate > 0.3% become ineligible for mitigation (delivery-support escalations) |
| November 2025 | Gmail "ramping up its enforcement on non-compliant traffic" — non-compliant messages experience disruptions including temporary and permanent rejections |
Mitigation eligibility
Google's bulk-sender escalation (mitigation) form only helps senders who already comply:
- Ineligible while user-reported spam rate is > 0.3%.
- Eligibility returns once spam rate stays below 0.3% for 7 consecutive days.
- Full authentication (SPF, DKIM, DMARC) and working one-click unsubscribe are prerequisites.
- Spam rate and other Postmaster Tools data are calculated and updated daily.
Non-compliance error codes
Gmail signals guideline failures with 4.7.x temporary errors (rate limiting) that escalate to 5.7.x permanent rejections. All Gmail SMTP errors carry the identifier gsmtp (and gcdp when caused by a Workspace administrator's custom rule).
| Requirement failed | Temporary (rate-limited) | Permanent (blocked) |
|---|---|---|
| PTR / reverse DNS | 451-4.7.23 (also 421-4.7.0 "no PTR record") | 550-5.7.25 |
| SPF or DKIM (unauthenticated) | 421-4.7.26 | 550-5.7.26 |
| SPF failed | 421-4.7.27 | 550-5.7.27 |
| DKIM failed | 421-4.7.30 | 550-5.7.30 |
| No DMARC record | 421-4.7.40 | 550-5.7.40 |
| From: not aligned with SPF/DKIM | 421-4.7.32 | 5.7.32 |
| No TLS | 421-4.7.29 | 550-5.7.29 |
| Unusual/unsolicited volume | 421-4.7.28 | 550-5.7.28 |
| Suspicious SPF record entries | 451-4.7.24 | 550-5.7.24 |
| IPv6 sending guidelines (PTR/auth) | — | 550-5.7.1 "does not meet IPv6 sending guidelines" |
The full error catalog, including format and reputation errors, is in Gmail troubleshooting.
Rate-limit recovery procedure (SMTP 4.7.28 quota errors): wait a minimum of 10 minutes, resume with a single connection; if successful, increase connections one at a time; if the single connection still fails, wait another 10 minutes.
Sending-practice recommendations (non-binding but weighted)
- Send from consistent IP addresses; use different IPs for different message types (e.g., notifications vs. promotions) and consistent
From:addresses per category — see Advanced IP segmentation. - Increase volume gradually, at consistent rates, avoiding bursts — see IP warm-up.
- On shared IPs, every sender's activity affects the shared reputation; monitor the IP against blocklists and in Postmaster Tools.
- Don't buy email lists, send unsolicited mail, or use opt-in forms with pre-checked boxes (regional law may prohibit them).
- Monitor affiliates and drop any that spam — "If your brand is associated with marketing spam, other messages sent by you might be marked as spam."
Display name rules
Sender display names must identify the sender exclusively and reflect a consistent, clear, accurate identity. Prohibited: subject-line text or message content in the display name ("URGENT REQUEST", "TIME IS RUNNING OUT"), deceptive emoji, the recipient's own name, or anything imitating a threaded conversation ("Re:"-style deception).
Compliance verification
Use Google Postmaster Tools — in particular the Compliance status dashboard — to check each requirement, and the Spam Rate dashboard to track the 0.10%/0.30% thresholds. Compliance-status changes can take up to 7 days to reflect after a fix.