Understand Why Your Emails Aren't Reaching the Inbox

A company moves its newsletter from one email platform to another. The migration goes smoothly. Campaigns send, the dashboard shows them as delivered, and no one spots that the new platform was never set up to sign mail with the company’s own domain. Three weeks later, clicks from Gmail recipients have fallen sharply while Outlook looks normal. Marketing assumes the content got worse.

“Delivered” only means the receiving server accepted the message. Where it went after that, inbox, spam or a promotions tab, is a separate decision made by the mailbox provider. This page is about finding out why that decision is going against you.

Why are my emails going to spam?

Your emails go to spam when a mailbox provider either can’t verify that you really sent them, or has learned from past behavior that its users don’t want them. Almost every deliverability problem traces back to one of those two things.

The first is technical: authentication records that are missing, broken or not aligned with the address in your From line. The second is reputation: built up over time from bounce rates, spam complaints, how recipients engage, and how your sending patterns look. Content can play a part, but it is rarely the root cause on its own. If a single campaign landed in spam, it may have been that campaign. If it keeps happening, it’s almost always the setup or the sending habits behind it.

Following one message from send to inbox

When you hit send, your platform hands the message to the recipient’s mail server. That server checks whether the sending domain has authorized the platform to send for it, and whether the message carries a valid cryptographic signature. It then checks the domain’s DMARC policy to see whether those results line up with the visible From address.

Next comes reputation. Gmail, Yahoo and Microsoft each keep their own view of your domain and sending IPs, shaped by how their users have treated your mail. A domain with a history of complaints or bounces to unknown users starts at a disadvantage.

Finally the receiving server filters the individual message, using all of the above plus content and engagement signals, and decides where it goes. Problems at any checkpoint carry forward to the next one.

What the review checks

SPF

SPF is a DNS record listing the servers allowed to send mail for a domain. The detail most people miss is that SPF is checked against the envelope sender (the Return-Path, or bounce address), not the From address your readers see. Many platforms use their own bounce domain by default, so SPF passes for them but does nothing for your domain under DMARC. We also check for the problems that break SPF outright: more than one SPF record on a domain, or a record that needs more than ten DNS lookups to resolve.

DKIM

DKIM adds a signature to each message, which the receiving server verifies with a public key published in your DNS. The question we ask is whose domain is doing the signing. If your platform signs with its own domain rather than yours, the signature is valid but doesn’t help your domain’s DMARC result or reputation. We check each sending source separately, because a business often has three or four: the marketing platform, the CRM, a helpdesk, an invoicing tool.

DMARC

DMARC tells receiving servers what to do when a message claims to come from your domain but fails authentication. A message passes DMARC when either SPF or DKIM passes and the domain that passed matches the domain in the From address. The policy can be set to none (monitor only), quarantine or reject. DMARC aggregate reports are the most useful evidence in the whole review, because they show every source sending mail as your domain, including ones nobody remembered.

Domain setup and platform configuration

We look at how your domains are organized: whether marketing, transactional and sales mail share one domain or are separated, whether a custom return path and tracking domain are configured, and whether your forward and reverse DNS are in order where you use dedicated IPs. We also check the platform settings that affect delivery, such as how hard bounces are suppressed, how unsubscribes are processed, and whether the List-Unsubscribe headers are present.

Sender reputation, bounces and complaints

We review the data your platform and the mailbox providers make available: bounce types and rates by provider, spam complaint rates, and where you have access, Google Postmaster Tools and Yahoo’s Sender Hub. A rise in bounces to addresses that don’t exist usually points at list sources. A complaint spike after a specific campaign points at targeting or frequency.

Engagement and list quality

How was the list built? When was each segment last sent to? How many contacts haven’t opened or clicked in a year and still receive every campaign? Mailbox providers notice when large parts of a list ignore you. Purchased lists, old imports and forms without confirmation tend to show up here.

What do Gmail, Yahoo and Microsoft require from bulk senders?

Since 2024, Google and Yahoo have required bulk senders to authenticate their mail, make unsubscribing easy and keep spam complaints low. Microsoft introduced similar authentication rules for Outlook.com consumer addresses in 2025. In practice that means:

• Authentication. Both SPF and DKIM set up for your sending domain, plus a published DMARC record. A policy of p=none is the minimum. The From domain must align with SPF or DKIM.
• One-click unsubscribe. Marketing and subscribed messages need List-Unsubscribe headers supporting one-click unsubscribe (the RFC 8058 method), and opt-outs must be honored within two days.
• Spam rate. Google asks bulk senders to keep the spam rate reported by its users below 0.3%, and recommends staying under 0.1%. Yahoo also uses 0.3% as its stated limit.

Google defines a bulk sender as one sending close to 5,000 or more messages a day to personal Gmail accounts, and once that applies, it continues to apply. Google began stepping up enforcement in late 2025, including temporary and permanent rejections for non-compliant mail. Microsoft’s rules apply to domains sending more than 5,000 messages a day to Outlook.com, Hotmail and Live addresses, with non-compliant mail first routed to Junk.

These are the minimum. Meeting every one of them doesn’t guarantee inbox placement. It just means the providers won’t penalize you for the basics.

What you get from the review

A written findings report, organized by priority rather than by protocol. For each issue you’ll see the evidence we found, why it matters, how severe it is, and who would typically fix it: your DNS administrator, your marketing team, or a platform setting.

We also tell you what’s fine. Knowing that your DKIM is correctly aligned saves your team from spending another week on it.

Then a short call to walk through the findings and answer questions. Some teams take the report and fix everything internally. Others want help with the work.

Review or remediation?

This service is the diagnosis. If the findings show that recovery will take a structured plan, such as cleaning a large inactive segment, moving to a new sending domain, rebuilding volume gradually or setting up separate infrastructure for cold outreach, that’s our deliverability improvement service. It’s hands-on, runs over several weeks and includes monitoring as reputation recovers.

Starting with the review means the remediation plan is based on evidence rather than guesswork, and you only pay for the fixes you actually need.