What are inbound vs outbound email threats?
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Think of email threats like traffic on a two-way street. Some threats are heading toward you. Others are heading out from you. Both can cause serious damage, just in different ways.
Inbound threats are attacks that land in your users' inboxes. Phishing emails try to steal credentials or personal data. Malware attachments install harmful software when opened. Malicious links redirect users to fake login pages or drive-by download sites. Social engineering messages manipulate people into wiring money or sharing sensitive information. The goal of inbound protection is to catch these before they reach a real person.
Outbound threats start from inside your own infrastructure. A compromised account gets hijacked and starts blasting spam to thousands of addresses. An infected machine on your network uses your domain to distribute malware. Someone leaks sensitive data by emailing it out. The danger here isn't just that harm reaches others. It's that your domain and IP reputation take the hit, and once you're on a blocklist, getting off is a serious project.
That reputation angle is where outbound threats get personal for email senders. If your domain is caught sending malicious traffic, mailbox providers like Gmail and Outlook will start treating your legitimate emails with suspicion too. Your newsletters, receipts, and password reset emails all suffer. Setting up authentication records like SPF, DKIM, and DMARC is a core part of outbound protection because they make it much harder for bad actors to send email that appears to come from your domain.
Which direction should you prioritize? Honestly, both matter and they're not competing. Inbound protection keeps your people safe. Outbound protection keeps your reputation intact. Most organizations find that inbound threats affect more users day to day, but a single outbound incident can do longer-lasting damage to your sending reputation.
If you're not sure whether your domain is currently flagged anywhere, you can run a free check with our blocklist checker. And if something's actively broken, the SOS hotline is there (and free).
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