Inbox delivery depends on your domain setup, the people you email, your sending history and the receiving mailbox provider. Postly provides sending safeguards; Gmail, Outlook, Yahoo and other providers decide where each message appears. No provider can promise that every marketing email will reach the inbox.
For example, a shop moving its newsletter to Postly should authenticate its domain, preserve every previous unsubscribe, test the message and start with recent subscribers who asked for updates. Importing an old customer database and immediately emailing everyone can damage its reputation even when DNS is correct.
Use this guide before your first campaign and whenever you change domains, import an audience or notice more bounces or spam placement. For the editor and scheduling steps, see Send and measure an email campaign.
1. Authenticate a domain you control
Before launching, verify SPF, DKIM and the effective DMARC policy. Resolve invalid or conflicting records before sending. A successful Postly ownership check alone does not replace this review.
Open Products → Email → Settings → Sending domains. Add your sending domain, publish the exact ownership TXT and DKIM CNAME records shown by Postly, then select Check verification. Copy the full record values carefully. Preserve existing website, company-mail and verification records.
Use an email address on that verified domain. Choose a recognizable sender name and a reply-to address that someone monitors. A reader should understand who sent the message without opening it. Tests require a verified domain too.
These three authentication methods serve different purposes:
| Method | What it checks | What to do |
|---|---|---|
| SPF | Whether the sending server is authorized for the message's return-path domain | Follow the sending service's exact DNS instructions. Keep one SPF record per DNS name; merge authorized services into it instead of adding competing records. |
| DKIM | Whether a cryptographic signature matches the signing domain and the message has remained intact | Publish Postly's records and keep DKIM signing enabled. A record that was verified previously is insufficient if signing has since been disabled. |
| DMARC | Whether SPF or DKIM passes and its authenticated domain aligns with the visible From domain | Ask your DNS administrator to publish or verify the applicable DMARC policy and monitor reports. |
Alignment means that the authenticated domain matches the visible sender
under the domain's DMARC rules. For example, under relaxed alignment,
bounce.example.com and a visible sender at example.com can align. Strict
alignment requires an exact domain match. A passing SPF check on a provider's
own domain alone does not establish alignment with your business domain.
Postly's domain check reports DKIM signing, a DMARC check at the domain you entered, and the configured return-path state. If it finds no DMARC record at a subdomain, a parent-domain policy may still apply. Check parent domain means your DNS administrator must confirm the effective policy; it is not proof that DMARC is absent. A lookup failure is also different from a missing record.
Set up DMARC reporting before tightening policy
A DMARC policy with p=none can be a sensible monitoring starting point. Add a
monitored aggregate-report destination using the rua tag. For example,
v=DMARC1; p=none; rua=mailto:dmarc-reports@example.com is illustrative: replace
the domain and mailbox with a reporting service or address you control. Do not
paste the example unchanged. External reporting destinations may require
additional authorization records supplied by the reporting service.
Review reports for all legitimate senders, including company email, billing
and support services. Move to quarantine or reject only after confirming
those senders authenticate correctly. Stronger policy helps prevent spoofing;
changing policy alone does not guarantee inbox placement.
Understand the return-path
The return-path handles delivery failures and can differ from the visible From address. A custom return-path needs the service's prescribed SPF and MX records. Postly shows whether an existing custom return-path is verified or pending. Ask support about configuring one; do not invent records or replace your business's incoming-mail MX records. Aligned DKIM can satisfy DMARC even when the sending provider's default return-path is used.
Confirm the result in a received test email's authentication headers. DNS checks alone cannot establish how an actual message was authenticated.
2. Send only to people who expect your message
Use subscribers who knowingly requested this type of email. Do not use bought, scraped or rented lists. A public email address, a social follower or an account registration alone does not establish marketing permission.
State what people will receive and how often when they subscribe. Where your signup process supports it, use a confirmation email so people confirm that the address is theirs. Keep the permission source and date. Do not describe an imported address as confirmed unless that confirmation actually happened.
When moving services, import previous unsubscribes, hard bounces and complaints alongside active subscribers. Review invalid rows and duplicates. An email validation service can find some address problems, but cannot prove consent or guarantee that an address will accept your campaign.
For example, someone requesting a single guide should receive that guide. They should not silently join unrelated daily promotions. Explain and obtain permission for any additional subscription.
See Email contacts and lists for preserving statuses during imports and exports.
3. Increase volume carefully
Start with recent, consenting subscribers and a consistent schedule. Review delivery failures, complaints, replies and meaningful engagement before expanding. A new domain or a long-unused audience needs particular care.
Do not jump from a small test to your entire historical database. There is no universal warm-up timetable: the appropriate pace depends on observed results, provider approval and the available sending capacity. Do not buy artificial opens, clicks or replies to simulate a good reputation.
Pause expansion when results worsen. Review the source of the affected addresses and stop emailing people who no longer want the messages. Do not repeatedly send re-engagement campaigns to an unresponsive list. Preserve all opt-outs when reducing or rebuilding an audience.
Your subscription's send allowance and your approved sending speed are different. A scheduled time is the earliest dispatch time, not a promise that every recipient will receive the message then. Check the current capacity in the dashboard before planning a time-sensitive campaign.
4. Send a useful, recognizable message
- Use an honest subject that matches the content. Do not add
Re:orFwd:to simulate a conversation. - State the useful information early and give readers one clear next step. For a shop update, explain what is available, why it is relevant and where to find it.
- Use working HTTPS links to recognizable destinations. Avoid unnecessary redirects and public link shorteners.
- Check mobile layout, image alternatives, the plain-text version, your business postal address and the unsubscribe footer.
- Make opting out easy. Postly adds an unsubscribe footer and one-click unsubscribe headers for managed campaigns. Do not hide, remove or work around them.
There is no magic list of words or image-to-text ratio that guarantees inbox delivery. Clear content helps people recognize wanted email; it cannot repair missing permission or a poor sending reputation.
5. Test delivery and monitor reputation
Use the owner test before sending a campaign. With appropriate permission, also check controlled Gmail, Outlook and Yahoo mailboxes. Inspect placement, formatting, links, reply-to details and SPF, DKIM and DMARC results. A successful test is evidence for that message and mailbox, not your entire audience.
Gmail's Promotions tab is an inbox category, not the spam folder. Do not promise Primary-tab placement. Avoid asking recipients to generate artificial engagement; let interested readers choose their own mailbox preferences.
Domain owners should use Google Postmaster Tools where sufficient sending volume makes data available. Aim to keep Gmail's reported spam rate below 0.1% and avoid reaching 0.3%. For example, one complaint per 1,000 messages is already 0.1% by simple arithmetic; the displayed Gmail rate uses Google's own measurement and denominator. See Google's sender guidelines.
Gmail does not provide individual spam complaints to Amazon SES. Zero complaints in Postly's provider events therefore does not prove that nobody marked a message as spam. Postmaster data may be delayed or unavailable for small volumes. Read AWS's feedback limitations.
Review results by receiving provider where data permits. Opens can be inflated by privacy features or hidden by blocked tracking, and automated scanners can produce clicks. Do not use opens alone as proof of subscriber interest.
6. Troubleshoot without creating duplicate sends
| What you see | Practical next step |
|---|---|
| Domain verification fails | Check the exact DNS names and values, DKIM signing, and propagation. Retry verification after corrections. |
| DMARC lookup is unavailable | Retry the DNS check. Ask your administrator to verify the effective policy; do not replace records because a lookup timed out. |
| A custom return-path stays pending | Have your administrator compare its SPF and MX records with the service's exact instructions. |
| Accepted but no delivery confirmation | Wait for feedback and review the original campaign. Acceptance does not establish final delivery. |
| Delivered but found in spam | Inspect that message's authentication, audience permission and recent reputation. Correct the cause before increasing volume. |
| Bounce or complaint rates increase | Stop expansion and review the affected audience source. Keep exclusions; contact support if sending is held. |
| Sending is paused or confirmation is uncertain | Keep the original campaign and receipts. Ask support to investigate before any retry. Do not duplicate the campaign just to force another attempt. |
For support, provide the campaign reference, approximate send time and timezone, receiving provider, the displayed error and a redacted authentication result from a mailbox you control. Never send passwords, access keys, complete audience exports or another person's private email content.
Read How Postly protects email delivery for the safeguards built into managed sending, and sending limits and metric definitions for interpreting reports.
Provider references
- Google email sender guidelines
- Yahoo sender requirements and best practices
- Amazon SES DMARC and alignment
- Amazon SES custom return-path setup
Provider requirements can change. Check the current provider documentation before a major sending change.