First, confirm the problem
Spam placement complaints often come from one or two readers. Before changing anything, send the same issue to test addresses you control at Gmail, Yahoo and any other mailbox providers common on your list, and note where each lands. If one provider places you in spam and others do not, focus on that provider's published requirements. If all of them do, the cause is more likely your domain setup or your list.
Write down the date, issue, and result for each test. You will compare against this after each fix, changing one thing at a time.
The five checks at a glance
Work top to bottom. Each later check assumes the earlier ones pass.
| Order | Check | Requirement or threshold | Where it comes from |
|---|---|---|---|
| 1 | Authentication | SPF or DKIM for all senders; SPF, DKIM and DMARC (p=none allowed) plus From alignment for bulk senders; DKIM key at least 1024 bits, 2048 recommended by Google | Google sender guidelines; Yahoo best practices |
| 2 | List source | Permission-based lists only; nothing bought, loaned, rented or acquired from a third party | MailerLite Anti-Spam Policy and Terms |
| 3 | Complaint rate | Below 0.1%, never 0.3% or higher at Gmail; below 0.3% at Yahoo; above 0.2% may trigger MailerLite suspension | Google; Yahoo; MailerLite |
| 4 | Content and unsubscribe | One-click List-Unsubscribe headers plus a visible link; Yahoo asks that unsubscribes be honored within 2 days | Google; Yahoo |
| 5 | Volume | Consistent rate, no sudden spikes, slow increases to engaged readers | Google sender guidelines |
Check 1: authentication on your own domain
Google requires all senders to set up SPF or DKIM, and senders of about 5,000 or more messages a day to personal Gmail accounts to set up SPF, DKIM and DMARC, with the From domain aligned to SPF or DKIM. Google's FAQ says anyone who reaches that volume once is permanently treated as a bulk sender. Yahoo's requirements match: SPF or DKIM for everyone, both plus a DMARC policy of at least p=none for bulk senders.
In MailerLite, authentication means adding the DKIM CNAME, SPF TXT and verification TXT records it provides, which must match exactly. If you send from a gmail.com or similar free address, you cannot authenticate that domain yourself; move to an address on a domain you own.
Check 2: where the list came from
Complaints and spam placement follow people who did not expect your email. MailerLite's policy bans addresses bought, loaned, rented or otherwise acquired from a third party, does not allow pre-ticked opt-in boxes, and does not allow addresses you have not emailed in the last two years. Even if your tool accepted the import, mailbox providers see the reaction.
Segment your list by source and send the next issue only to recent form signups. If placement improves, the problem is in the other segments. Remove or re-permission them rather than continuing to send.
Check 3: complaint rate, measured correctly
Google measures spam rate daily in Postmaster Tools and says senders above 0.3% are not eligible for mitigation until they stay below it for seven days in a row. Yahoo notes it calculates spam rate based on mail delivered to the inbox, so your own figures may differ from Yahoo's.
A quick example: 4 complaints from 2,000 delivered messages is 0.2%. That is already double Google's 0.1% target and right at MailerLite's line, which triggers on anything more than 0.2%. Common fixes are a clearer reminder of why the reader signed up, a more prominent unsubscribe link, and removing long-inactive readers.
Check 4: content and unsubscribe
Google asks bulk senders to support one-click unsubscribe with the List-Unsubscribe-Post header set to List-Unsubscribe=One-Click and a List-Unsubscribe URL, plus a visible unsubscribe link in the body. Yahoo asks for the same header, a clearly visible link, and that unsubscribes be honored within 2 days. Check whether your tool adds these headers: send yourself a copy and view the original message headers.
Google also requires messages to follow RFC 5322 formatting and not impersonate Gmail From headers. Keep your From name and address consistent from issue to issue so readers recognize you.
Check 5: sending volume and pattern
Google advises sending at a consistent rate, avoiding bursts and sudden spikes if you lack a history of large volumes, and starting with low volume to engaged readers. If messages are deferred or bounced, it says to reduce volume until errors drop, then increase slowly again. Yahoo asks that bulk and marketing mail not share IPs with transactional or user mail.
If you recently imported a large list or doubled frequency, that change alone can explain the drop. See our domain warm-up guide for an example ramp.
When switching tools is the right answer
- All five checks pass and the problem persists across several issues.
- Your tool cannot authenticate your domain or add one-click unsubscribe headers.
- You cannot see complaint and bounce rates per campaign in your current tool.
- You have a business reason to move anyway, such as price or features.
- If you do switch, follow the same five checks on the new tool and ramp volume rather than sending the full list on day one.
Questions before you decide
What spam rate is too high?
Google recommends staying below 0.1% and never reaching 0.3% in Postmaster Tools. Yahoo also says to keep spam rate below 0.3%. MailerLite's anti-spam policy lists complaints above 0.2% as a suspension trigger.
Do I need DMARC for a small newsletter?
Google requires SPF, DKIM and DMARC for senders of 5,000 or more messages a day to Gmail accounts, and SPF or DKIM for everyone. Setting up all three is still the sensible baseline at any size.
Will switching email providers fix spam placement?
Not if the cause is list source, complaints or authentication on your own domain. Those travel with you. Fix them first, then judge the provider.
Sources & verification
Product details and prices can change. Check the linked provider before buying.
- Google: Email sender guidelines Accessed 29 Oct 2026
- Google: Email sender guidelines FAQ Accessed 29 Oct 2026
- Yahoo Sender Hub: Best practices and requirements Accessed 29 Oct 2026
- MailerLite Anti-Spam Policy Accessed 29 Oct 2026
- MailerLite Help: Domain authentication Accessed 29 Oct 2026
Sources link directly to providers. Product buttons may use separately labeled affiliate links. Read our disclosure.