What this is
This guide explains how to reduce the chances of your emails being flagged as spam and improve overall email deliverability.
Important: These are best practices, not guarantees. Spam filtering varies by provider and user behavior, two recipients can receive the same email and experience different outcomes.
What affects email deliverability
At a high level, spam filtering is influenced by two main factors:
- Domain reputation
- Email content and formatting
Both must be properly managed to improve deliverability.
1. Domain reputation
Your domain reputation determines whether email providers trust your messages.
Set up SPF, DKIM, and DMARC
These authentication methods help verify that your emails are legitimate.
- SPF – defines which servers can send emails from your domain
- DKIM – adds a signature to verify message authenticity
- DMARC – defines how failed authentication is handled
Without these, emails are more likely to be flagged or blocked.
Note: These settings are configured through your domain/email provider, not Propensity.
Use a dedicated domain for outreach
Avoid sending outreach emails from your primary domain.
- Use a separate domain or subdomain
- Reserve your main domain for business communication
This helps protect your main domain’s reputation.
Warm up your mailbox
New domains and mailboxes have no reputation.
Sending high volumes too quickly can trigger spam filters.
Best practices:
- Start with low volume
- Increase gradually
- Ensure emails are opened and replied to
You can also use email warm-up tools to accelerate this process.
2. Email content and formatting
Even with a strong domain, poor email formatting can trigger spam filters.
Avoid links in early outreach
- Do not include links in first-contact emails
- Remove links from signatures if possible
Links are commonly flagged in cold outreach.
Avoid images and attachments
- Do not include images or attachments in early emails
- Even images in signatures can impact deliverability
Use plain text whenever possible.
Keep formatting simple
Avoid:
- Bold, italics, or underlining
- Multiple fonts or colors
Use clean, plain-text formatting.
Keep messages concise
- Avoid long emails
- Focus on clear, simple messaging
Overly long content can reduce deliverability and engagement.
Avoid spam-triggering language
There is no fixed list of “banned” words, but avoid:
- Urgent or aggressive phrasing
- Overly promotional language
- Messages that feel automated or unnatural
A good rule:
If the email feels like spam, it may be treated as spam.
Test and iterate
Monitor performance across different versions of your messaging.
- Compare bounce rates
- Identify patterns
- Adjust content accordingly
Additional best practices
- Ensure your mailbox is properly configured before sending campaigns
- Monitor bounce rates and engagement
- Avoid sudden spikes in sending volume
- Maintain consistent sending behavior
Important notes
Avoiding spam filters requires both:
- A properly configured and trusted domain
- Clean, simple, and natural email content
Following these best practices will improve deliverability and increase the likelihood that your emails reach the intended inbox.