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Advanced Deliverability - Lesson 5
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Content and Formatting: Writing Emails That Reach the Inbox
The words you choose and how you format them directly impact whether your emails reach the inbox. Spam filters analyze email content looking for patterns associated with unwanted messages. Understanding what triggers these filters helps you craft messages that communicate effectively while maintaining strong deliverability.
Common Content Triggers
Certain words and phrases appear so frequently in spam that their presence triggers increased scrutiny. Terms like free, guarantee, click here, and act now have been abused by generations of spammers. While using these words will not automatically send your email to spam, accumulating multiple triggers in a single message increases risk.
Beyond individual words, spam filters look for patterns in how content is structured. All caps text, excessive exclamation marks, and text designed to evade filters like writing free as fr-ee all signal potential spam. The more your email looks like classic spam formatting, the worse your deliverability will be.
Images present another challenge. Emails that are primarily images with minimal text often get filtered because spammers use images to hide their content from text-based filters. A healthy ratio of text to images keeps your emails looking legitimate.
Link Considerations
Links in your emails receive special attention from spam filters. Including too many links in a single email raises red flags. Links to suspicious domains, URL shorteners, or newly registered domains can trigger filters even if your sending domain has strong reputation.
The domains you link to become associated with your sending reputation. Linking to high-quality, established domains is generally safe. Linking to domains with poor reputation or domains that host problematic content can damage your deliverability.
Your tracking domain, as discussed in previous lessons, also matters here. Shared tracking domains can carry negative reputation from other senders. Custom tracking domains isolate you from this risk but need to be warmed up and maintained carefully.
Plain Text and HTML
Emails can be sent in plain text, HTML, or multipart format that includes both. Each format has implications for deliverability. Plain text emails avoid many formatting-related triggers and often achieve better inbox placement for cold outreach. HTML emails enable richer formatting but introduce more variables that can affect deliverability.
When using HTML, keep the code clean and simple. Complex HTML with lots of formatting, embedded styles, or code generated by word processors often contains artifacts that trigger spam filters. Simple, straightforward HTML renders reliably and avoids technical triggers.
Multipart emails that include both plain text and HTML versions provide a fallback for email clients that do not render HTML well. This approach is generally considered best practice, though it does require maintaining two versions of your content.
Personalization and Spam Filters
Personalization helps deliverability by making each email unique. Identical emails sent to many recipients look like spam by definition. Dynamic content that changes based on recipient information creates variation that makes your campaigns appear more legitimate.
However, heavy personalization using merge fields can sometimes backfire. If your personalization data is incomplete or incorrect, you end up sending emails with obvious placeholder text or awkward phrasing. Testing your personalization thoroughly before launching campaigns prevents these embarrassing errors.
The key is finding balance. Enough personalization to create meaningful variation and relevance, but not so much complexity that you introduce errors or make your messages feel artificially generated.
Testing Before Sending
Given all the factors that influence content-based filtering, testing your emails before sending to your full list is essential. Spam testing tools analyze your content and predict how likely it is to trigger filters. Inbox placement tests send your email to test accounts across different providers and report where they land.
Make testing a standard part of your campaign development process. Write your emails, test them, revise based on the results, and test again until you achieve strong predicted deliverability. The few minutes spent testing can save you from campaigns that underperform due to avoidable content issues.
Video transcript
Now let's talk about one of the most misunderstood concepts in email deliverability, catch all domains. A catch all domain is basically a mail server that says, sure, we accept all emails even if the address doesn't actually exist. On the surface, that sounds fine. But when you send it to too many catch all addresses, those invisible bouncers start piling up behind the scenes.
That's why it instantly runs real time catch all detection. It flags those risky addresses before you actually send. You can decide how to handle them. Either exclude them completely or put them into a separate slow warm up campaign.
This is one of those small settings that makes a massive difference because every bad send chips away your domain reputation, and you only get so many chances before Gmail and Outlook start flagging you. So when in doubt, always verify. Instantly's built in system does it automatically saving you hours of manual cleaning or external verification tools.
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