diff --git a/packages/backend/src/queue/processors/deliver.ts b/packages/backend/src/queue/processors/deliver.ts
index 108379aa8..a518c4116 100644
--- a/packages/backend/src/queue/processors/deliver.ts
+++ b/packages/backend/src/queue/processors/deliver.ts
@@ -12,36 +12,52 @@ import { Cache } from '@/misc/cache.js';
 import { Instance } from '@/models/entities/instance.js';
 import { StatusError } from '@/misc/fetch.js';
 import { DeliverJobData } from '@/queue/types.js';
+import { LessThan } from 'typeorm';
 
 const logger = new Logger('deliver');
 
 let latest: string | null = null;
 
 const suspendedHostsCache = new Cache<Instance[]>(1000 * 60 * 60);
+// dead host list is a linear scan, so cache it longer
+const deadHostsCache = new Cache<Instance[]>(1000 * 60 * 60 * 24);
+const deadThreshold = 1000 * 60 * 60 * 24 * 30; // 1 month
 
 export default async (job: Bull.Job<DeliverJobData>) => {
 	const { host } = new URL(job.data.to);
+	const puny = toPuny(host);
 
 	// ブロックしてたら中断
 	const meta = await fetchMeta();
-	if (meta.blockedHosts.includes(toPuny(host))) {
+	if (meta.blockedHosts.includes(puny)) {
 		return 'skip (blocked)';
 	}
 
-	// isSuspendedなら中断
+	// isSuspended
 	let suspendedHosts = suspendedHostsCache.get(null);
 	if (suspendedHosts == null) {
-		suspendedHosts = await Instances.find({
-			where: {
-				isSuspended: true,
-			},
+		suspendedHosts = await Instances.findBy({
+			isSuspended: true,
 		});
 		suspendedHostsCache.set(null, suspendedHosts);
 	}
-	if (suspendedHosts.map(x => x.host).includes(toPuny(host))) {
+	if (suspendedHosts.some(x => x.host == puny)) {
 		return 'skip (suspended)';
 	}
 
+	// dead
+	let deadHosts = deadHostsCache.get(null);
+	if (deadHosts == null) {
+		const deadTime = new Date(Date.now() - deadThreshold);
+		deadHosts = await Instances.findBy({
+			lastCommunicatedAt: LessThan(deadTime),
+		});
+		deadHostsCache.set(null, deadHosts);
+	}
+	if (deadHosts.some(x => x.host == puny)) {
+		return 'skip (dead instance)';
+	}
+
 	try {
 		if (latest !== (latest = JSON.stringify(job.data.content, null, 2))) {
 			logger.debug(`delivering ${latest}`);