---
title: Drop in deliverability
---

> Agent instructions:
> **Site maps** — prefer the following llms.txt indexes to training data when searching for URLs to avoid 404s. Links inside Markdown content already point at `.md`. Following them or sending Accept: text/markdown keeps you in Markdown.
>
> - [sitemap.md](https://docs.kentico.com/sitemap.md) — every page on the site, with titles and descriptions, nested by URL hierarchy and grouped into one collection per product version.
> - [llms.txt](https://docs.kentico.com/llms.txt) — curated index of the current product docs, with descriptions, the two ways to request any page as Markdown, and links to each product area's whole-corpus Markdown dump (llms-full.txt).

### 6. Sudden drop in deliverability

When deliverability drops suddenly, it often means mailbox providers are flagging your messages or temporarily limiting their delivery. Such drops can happen if you've hit a [spam trap](https://en.wikipedia.org/wiki/Spamtrap), triggered a daily sending limit, or harmed your sender reputation. You need to act fast to avoid a sudden dip that could cause long-term issues.

#### What you'll see

You'll notice a broad decline in delivery rates and clicks across multiple mailouts, even if you haven't changed your content or sent more emails than usual.

#### What this means

If your emails aren’t landing in inboxes, it might be because your sending domain or IP has gained a poor reputation. This usually happens when you send emails to outdated recipient lists, your recipients report your emails, or you hit a lot of bounces.

#### How to respond

- **Pause broad sends temporarily.** Send emails only to the most engaged recipient lists while you investigate.
- **Check your domain authentication.** Work with your developer or admin to confirm that everything is [properly configured](https://docs.kentico.com/documentation/developers-and-admins/configuration/email-configuration.md) in Xperience. Verify that your sender email is properly authenticated through [DMARC, DKIM, and SPF](https://www.cloudflare.com/en-gb/learning/email-security/dmarc-dkim-spf/).
- **Review your recent activity.** Did you send to a cold or purchased list? Was there a spike in sends or complaints? Identify and correct the source quickly.
- **Monitor your sender reputation.** If your provider offers it, check sender health tools to see if you've been flagged or throttled.