Do spam filters check your website too?

You've spent time building your email, your subject line is solid, your list is clean. Then a filter quietly checks every URL you linked to and decides your message looks suspicious. Yes, spam filters do look at the websites you link to. And yes, a newly registered or low-reputation domain can tip the scales against you.

Here's what's actually happening. When your email arrives at a mail server, the filter doesn't just read your words. It follows your links (or at least resolves where they point) and checks those domains against reputation databases and blocklists. A domain that was registered last Tuesday, has no web history, and no SSL certificate raises an immediate flag. The filter doesn't know it's your new landing page. It just knows it looks like every phishing setup it's seen before.

The risk is higher when your sending domain itself is new. If you're sending from a domain you just registered and linking to a website on that same domain, you've stacked two trust signals against you at once. Filters weight domain age because spammers burn through fresh domains constantly. An established domain with a real traffic history and valid SSL reads as a completely different animal.

What actually causes problems:

• Linking to a domain registered in the last 30 to 90 days with no prior reputation
• Using URL shorteners that hide where the link actually goes (filters distrust the obscured destination)
• Mixing your legitimate links with a single link to a domain that's been flagged or compromised
• Linking to a domain that doesn't match your sending domain and has no SSL

What doesn't cause much of a problem:

• Linking to well-known domains with years of reputation (your own established site, major platforms)
• One or two links total, pointing to real pages with real content
• Consistent link domains that match who you say you are as a sender

One thing worth knowing: if you're a sender with good engagement history, filters extend more trust to your links. The same URL in an email from a brand with strong reputation and one from an unknown sender gets evaluated very differently. Link reputation doesn't exist in isolation. It's part of the full picture the filter builds about you.

If your domain is new, the most practical move is to warm up your sending reputation patiently before linking out to fresh pages. Stick to your main domain, keep SSL valid, and don't rush volume. You can also check whether any of your domains are sitting on blocklists right now with our free Blocklist Checker. If something looks off, that's worth fixing before your next send.