Deliverability for a small sender comes down to authentication, list quality, and consistency. Authentication is a one-time technical task. List quality is a permanent discipline. Consistency is the part nobody mentions: sending nothing for eight months then blasting two thousand people is the single most reliable way to end up in a spam folder.
The three records
These are published in your domain's DNS and let receiving providers verify that mail claiming to be from you actually is. Major providers tightened requirements for bulk senders in 2024, and correct authentication moved from good practice to a precondition.
| Record | What it does |
|---|---|
| SPF | Lists which servers are permitted to send mail for your domain |
| DKIM | Adds a cryptographic signature proving the message was not altered |
| DMARC | Tells receivers what to do when the first two fail, and can report back to you |
Two practical notes. Your marketing platform and your regular mail provider both need to be authorised, and adding one while forgetting the other is a common cause of sudden delivery problems. And a DMARC record set only to monitor still gives you the reports, which are the most useful diagnostic available and cost nothing.
Reputation, and how it is actually built
Receiving providers decide based on how recipients have treated your mail previously. The signals that matter most:
- Complaint rate. People marking your mail as spam. The most damaging signal by a distance.
- Engagement. Opens and clicks, but also replies and messages moved out of spam, which carry more weight.
- Bounce rate. Sending to addresses that do not exist suggests a list you did not build.
- Consistency of volume. Sudden large increases look like a compromised account.
- Spam trap hits. Addresses that exist purely to catch senders using purchased or scraped lists.
The mistakes small senders make
Sending nothing, then sending everything
The most common pattern in small business email. Eight months of silence followed by a large campaign produces a spike in volume to a list that has forgotten you, which generates complaints, which damages reputation for months.
Regular modest sending outperforms occasional large sending, even where the total volume is identical.
Never removing anyone
Contacts who have not opened anything in a year are actively hurting you. They depress engagement rates and some become complaints or traps. Removing them feels like losing something and improves delivery for everyone remaining.
Sending from a no-reply address
It prevents replies, which are a positive signal, and it tells recipients you are not interested in hearing from them. Use a monitored address.
Importing an old list
A spreadsheet of addresses collected over years, imported at once, is the fastest route to a reputation problem. Beyond deliverability it is also the compliance issue described in CASL.
Using a brand new domain
A domain with no sending history is treated cautiously. Where you must, start with small volumes to your most engaged contacts and increase gradually.
Content factors, in proportion
These matter less than authentication and reputation, and they are not nothing:
- A reasonable ratio of text to images, since image-only messages are treated with suspicion
- Links pointing to domains with decent reputations, including your own
- A subject line describing the content rather than manufacturing urgency
- A plain text alternative alongside the formatted version
- Avoiding link shorteners, which are heavily associated with abuse
The old advice about avoiding particular trigger words is largely outdated. Filtering is behavioural now, and a message from a sender with good reputation to an engaged list arrives regardless of whether it contains the word free.
Diagnosing a problem
- Check your DMARC reports for authentication failures you did not know about.
- Check blocklists using any free lookup service, for both your domain and sending address.
- Send to test accounts across the major providers and see where each lands.
- Look at engagement by provider. A problem at one provider and not others points at reputation with that provider specifically.
- Check whether a form or account was compromised, since a site sending spam without your knowledge is a frequent cause of sudden collapse.
For a small sender with authentication in place, a genuine list, and a regular sending habit, deliverability is mostly a solved problem. The difficulties arise almost entirely from the three things above: no authentication, a list nobody consented to, or long silence broken by a sudden campaign.
Frequently asked questions
What are SPF, DKIM and DMARC?
Records published in your domain's DNS that let receiving providers verify mail claiming to be from you. SPF lists permitted sending servers, DKIM adds a signature proving the message was not altered, and DMARC states what receivers should do when the others fail.
Why do my emails go to spam?
Most commonly missing or incorrect authentication, a list that did not genuinely consent, or irregular sending. Long silence followed by a large campaign is particularly damaging because it combines a volume spike with a list that has forgotten who you are.
Should I remove subscribers who never open my emails?
Yes. Contacts who have not engaged in a year depress your overall engagement rate, and some eventually become complaints or spam trap hits. Removing them feels like a loss and improves delivery for everyone who remains.
Does using words like free trigger spam filters?
Largely not any more. Filtering is behavioural rather than keyword based, so a sender with good reputation writing to an engaged list will arrive regardless of particular words. Authentication and reputation matter far more than vocabulary.
Is it better to send often or occasionally?
Regular modest sending outperforms occasional large sending even at identical total volume, because sudden spikes resemble a compromised account and lists that have not heard from you generate complaints when you reappear.
How do I diagnose a deliverability problem?
Check DMARC reports for authentication failures, check blocklist lookup services for your domain and sending address, send test messages to accounts at each major provider, compare engagement by provider, and confirm no form or account has been compromised.
West Coast Media Solutions Inc. builds and hosts websites for businesses across Canada and operates a premium domain marketplace, both relevant interests to declare. Nothing here is legal advice; where obligations are described, confirm current requirements against the regulator or your own counsel.
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