With email providers like Gmail and Microsoft tightening security and bulk-sender rules each year1, it’s now imperative that marketers follow best practices to ensure their emails reach inboxes.
Below are practical deliverability best practices—starting with links and expanding to a few other key areas that can help your email reach your audience.
1. Use self-hosted, trustworthy links
Links should help recipients and reassure spam filters.
Leverage your own domain
• Link primarily to content on your own website (same domain or a clearly related subdomain as your sending address).
• Avoid linking out to lots of different third-party domains in a single email; many filters see multiple external domains as spammy2
Avoid URL shorteners
• Public shorteners (bit.ly, etc.) are heavily abused by spammers and some shortened domains end up on blocklists. Many filters distrust them by default.
• If you need tracking, use your email service provider’s (ESP) branded tracking domain or a custom domain instead.
Use clear, honest CTAs
• Let readers know where a link will take them:
o “Read the full case study”
o “Download the spec sheet (PDF)”
2. Limit the number of links
More links do not mean more value.
• For most B2B marketing or sales emails, 1–3 links is a practical ceiling. Industry reports suggest emails with 1–2 relevant links tend to see better engagement and fewer spam issues than those loaded with links3.
• Use one primary CTA (e.g., “View the guide”) and, at most, one or two supporting links (e.g., “Visit our site,” “Contact us”).
This keeps your message focused and reduces the chance of raising red flags in filters.
3. Be smart with attachments and files
Attachments are convenient for recipients but risky for deliverability.
• Avoid attachments, especially in cold or first-touch emails. Suspicious file types (ZIP, EXE, macro-enabled docs, etc.) are common malware vectors and can get messages blocked or filtered4.
• Instead, link to a file hosted on your site (e.g., a PDF on a landing page). That’s better for both deliverability and tracking.
4. Get the technical basics right
Strong content and smart links won’t help much if your technical setup is weak.
Make sure you’ve:
• Authenticated your domain with SPF, DKIM, and DMARC. Major providers like Microsoft and others are tightening requirements, especially for higher-volume senders, and these protocols are now considered table stakes for good deliverability.
• Send from a consistent domain or subdomain so inbox providers can build a clear domain reputation over time.
• Monitored for errors (DNS issues, failed authentication, bounces) and fixed them promptly.
Think of this as foundational plumbing. If it’s not right, nothing else works as well as it should.
5. Keep content and layout “deliverability-friendly.”
Filters look at more than just links.
Content
• Avoid “shouting” (ALL CAPS, excessive punctuation, spammy phrases like “FREE!!!” or “URGENT OFFER”).
• Focus on clear, relevant language and a reasonable text-to-image ratio.
Layout
• Ensure your templates are mobile-responsive
• Keep the structure simple: logo → headline → short copy → primary CTA link.
• Include a plain-text version as a fallback; this is still a positive signal to many providers.
6. Respect the inbox: list quality and sending behavior
Inbox providers pay close attention to how recipients react to your emails.
• Keep your list clean. Remove hard bounces, and consider re-engagement or sunsetting for chronically inactive contacts.
• Include a visible unsubscribe link and physical address. This is both a legal and best-practice requirement—and it helps maintain list quality.
Healthy engagement (opens, clicks, low complaint rates) sends a strong “this sender is wanted” signal, which improves inbox placement over time.
7. A quick checklist for your next campaign
Before you hit send, check:
• Links go primarily to your own domain or trusted domains
• You’re using no more than 1–3 links, with one primary CTA
• No public URL shorteners are used
• Files are linked, not attached (especially in outbound campaigns)
• SPF, DKIM, and DMARC are properly configured
• Content is clear, relevant, and not overly promotional
• There’s a visible unsubscribe link and physical address
• Your list is clean
Want help tightening up your email program?
Triad can help.
We work with B2B brands to design email programs that land in the inbox, support sales, and drive measurable results.
[Contact us] to talk about what an updated email and deliverability strategy could look like for your team.
Sources
1 https://martech.org/new-rules-for-bulk-email-senders-from-google-yahoo-what-you-need-to-know
2https://help.salesforce.com/s/articleView?id=mktg.pardot_content_and_spam_filters.htm&type=5
3https://smartreach.io/blog/how-links-impact-cold-email-deliverability
4https://www.emailaudience.com/email-deliverability-best-practices