https://senderaudit.com/blog/en/tags/reputation/Recent content in Reputation on Sender Audit BlogHugoenMon, 09 Feb 2026 00:00:00 +0000https://senderaudit.com/blog/en/understanding-blacklists/Mon, 09 Feb 2026 00:00:00 +0000https://senderaudit.com/blog/en/understanding-blacklists/<p>Your delivery rate drops suddenly. Your emails go to spam, or worse, they&rsquo;re rejected with <code>550 5.7.1 Service unavailable; client host blocked</code>. There&rsquo;s a good chance your IP or domain is on a <strong>blacklist</strong>.</p> <h2 id="what-is-an-email-blacklist">What Is an Email Blacklist?</h2> <p>A blacklist (or RBL, Realtime Blackhole List, or DNSBL, DNS-based Blackhole List) is a database that catalogues IP addresses and domains identified as spam sources or abusive senders.</p> <p>Receiving servers (Gmail, Outlook, ISPs, corporate servers…) query these lists in real time to decide whether to accept, filter, or reject an email.</p>https://senderaudit.com/blog/en/email-deliverability/Tue, 03 Feb 2026 00:00:00 +0000https://senderaudit.com/blog/en/email-deliverability/<p>You send emails, but do they actually reach the inbox? <strong>Deliverability</strong> is the rate at which your emails land in recipients&rsquo; inboxes, as opposed to the spam folder or outright rejection. It&rsquo;s a critical issue for any business that communicates via email.</p> <h2 id="why-your-emails-arent-arriving">Why Your Emails Aren&rsquo;t Arriving</h2> <p>ISPs (Gmail, Outlook, Yahoo, etc.) use hundreds of signals to decide the fate of each email. Here are the main ones:</p> <h3 id="1-dns-authentication">1. DNS Authentication</h3> <p>This is the absolute prerequisite. Without it, you&rsquo;re a stranger to ISPs.</p>