When marketing emails land in spam, changing the subject line is rarely a sufficient diagnosis. The cause may be technical, in how contacts were collected, in recipients' expectations or in the reputation of the infrastructure used. Check these layers one by one.
First find out whether the email was rejected, delayed, or accepted and moved to spam. Then check SPF, DKIM and DMARC on a real message, inventory all senders from the domain and review the list, complaints and unsubscribing. Correct DNS records are a necessary technical layer, but they don't guarantee the inbox.
"Delivered" and "in the inbox" are different things
The "delivered" status in the platform usually shows that the receiving server accepted the message. It doesn't prove which folder it landed in. Distinguish a permanent rejection, a temporary error and acceptance with spam classification.
The "Promotions" tab in Gmail is not the "Spam" folder either. Don't promise that every commercial email will land in the primary tab. The goal is an email that is recognizable, expected and accessible to the recipient.
A diagnostic order instead of random changes
| Signal | First check | What to record |
|---|---|---|
| Messages are rejected | The SMTP response and the provider's error | Code, domain, date, sender |
| Accepted, but in spam | Authentication and reputation | Headers and affected recipients |
| Problem in only one campaign | Segment, promise and frequency | The difference from previous campaigns |
| Problem after a new tool | The new sending source | Domain, IP, DKIM signature |
| Many complaints | Where the contacts came from and unsubscribing | When and what they signed up for |
Keep the original headers of sample emails. A screenshot of the "Spam" folder shows the symptom, but it doesn't give enough data for a technical check.
SPF, DKIM and DMARC: what to actually check
SPF describes the permitted sending sources for the domain. DKIM verifies the message signature. DMARC ties authentication to the visible From domain and its policy. Review the results in Authentication-Results, instead of relying only on a green checkmark when setting up the platform.
For sending to personal Gmail addresses, Google publishes basic and additional requirements for high volume. For bulk senders they include SPF, DKIM and DMARC, as well as the corresponding unsubscribe rules. Check the current conditions for your volume and message type in the official documentation.
Before a stricter DMARC policy, list all legitimate sources: the marketing platform, website, CRM, business mail, invoicing and the booking system. Otherwise a change meant to help the newsletter may affect valid business emails. Don't add a second SPF record as a separate fix; the configuration must be checked as a whole.
Example of checking one email
The hypothetical result spf=pass; dkim=pass; dmarc=fail doesn't mean everything is fine. Check the domains used and the alignment with From. Conversely, three successful checks don't prove a good reputation or wanted content.
Record which system sent the email, which From is visible, which domain signed it and what the receiving provider is. Compare a marketing message with a valid business message from the same organization. This shows whether the problem is general or limited to a specific flow.
The contact list may be the bigger problem
Split recipients by origin and expectation: newsletter subscribers, customers with a suitable communication preference, contacts from an old import and those of unknown origin. Having an address in the CRM doesn't automatically mean the person expects marketing campaigns.
Don't buy a list as a fix for low reach. Don't send to addresses with a permanent bounce or to people who have unsubscribed. Suppressing these contacts must work across all connected tools, not just in the latest campaign.
Check whether the promised frequency and content match the real emails. If the sign-up was for one document, a sudden daily series can generate complaints. With an unclear origin, first clarify the data and the applicable rules, instead of mass-sending a "confirmation" to unknown contacts.
Unsubscribing and reputation
For the relevant marketing and subscription messages, Gmail requires technical one-click unsubscribe at high volume. This is a mechanism in the headers, not just a link in the text. Also check the visible link, how the opt-out is processed and whether an unsubscribed contact gets re-added on the next sync.
Monitor bounces, complaints, delivery and domain reputation through the available tools, including Google Postmaster Tools when there's enough data. A low open count alone doesn't prove a spam problem: email clients' privacy protections can change this metric.
How to regain control over sending
- Keep the baseline metrics by provider and flow.
- Fix the confirmed technical problems and test again.
- Stop uncertain imports and fix the syncing of opt-outs.
- Start with relevant contacts who actually expect the messages.
- Change volume gradually based on real signals, without fake opens and artificial conversations.
- Monitor the result over a sufficient period; one test mailbox doesn't represent all recipients.
DigitaL+ treats deliverability as part of email marketing, especially for online stores. After fixing the problems, you can organize the priority email automations. For choosing a partner, see how to evaluate an email marketing agency.
Frequently asked questions
Does DMARC guarantee we won't land in spam?
No. Authentication doesn't replace reputation, recipients' expectations and list quality.
Does changing the domain help?
Not as an automatic solution. A new domain doesn't fix a bad contact origin or excessive frequency and may create new recognition problems.
How long does improvement take?
It depends on the cause and the sending history. A technical fix can be checked quickly; a change in reputation requires monitoring and can't be promised within a fixed time.
