What are the main causes of reputation damage?
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You've noticed emails landing in spam more often, or maybe you just got flagged on a blocklist. Before you can fix the problem, you need to know which of the usual suspects is actually to blame. Reputation damage rarely has a single cause, but it usually falls into a handful of categories that each leave a different fingerprint.
High complaint rates
This is the fastest path to inbox trouble. When recipients click "report spam" on your messages, mailbox providers like Gmail and Outlook take note immediately. A complaint rate above 0.1% is a yellow flag. Above 0.3% and you're in serious trouble. The usual culprits are sending to people who didn't explicitly opt in, or emailing a list that's gone cold without any re-engagement.
Spam trap hits
Spam traps are email addresses that aren't used by real people. They exist only to catch senders who have poor list practices. Hitting a recycled trap suggests your list has old, abandoned addresses. Hitting a pristine trap (one that never belonged to a real person) is a much stronger signal that you've sourced addresses from somewhere you shouldn't have. Both hurt, but pristine trap hits tend to trigger faster, harder consequences.
High bounce rates
A hard bounce rate above 2% tells mailbox providers and filters your list may contain purchased data, scraped addresses, or contacts that have simply aged out. Unresolved hard bounces compound over time. Each bounce you continue sending to makes the next one count against you more.
Authentication failures
If your SPF, DKIM, or DMARC records are broken or misconfigured, receiving servers can't verify you are who you say you are. This doesn't just look suspicious. It actively blocks the kind of reputation data from accumulating in the first place. You can't build a good reputation on top of failed authentication. Check yours now with our free SPF checker and DKIM lookup.
Volume or sending pattern spikes
Doubling your sending volume overnight, switching to a new IP, or sending after a long pause all look like classic spam behavior to filtering algorithms. ISPs expect consistent, predictable patterns. A sudden spike without gradual warmup can tank a sender score that took months to build.
Sending to disengaged recipients
Low open rates, no clicks, no replies. Over time, this pattern of one-sided sending tells mailbox providers that your emails aren't wanted, even if recipients haven't technically complained. Gmail in particular is known to silently filter senders whose messages go consistently ignored. This is called silent filtering, and it's sneaky because you won't see hard failures, just a slow fade in reach.
How to start diagnosing your situation
The fingerprints are different for each cause. High complaints show up in Gmail Postmaster Tools and feedback loop reports. Spam trap hits usually surface on blocklist entries from Spamhaus. Bounce rate problems are visible right inside your ESP dashboard. Authentication issues are easy to spot with a free tool. Volume spikes are usually something you caused intentionally without realizing the risk.
If you're not sure where to start, run a blocklist check on your domain and sending IP. It won't tell you everything, but it gives you a clear picture of whether the damage has already landed somewhere specific. Try our free blocklist checker to see where you stand right now.
Still can't pin it down? That's what the SOS hotline is for. Free, no pitch, just someone who'll help you figure out what's actually broken.
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