# SMTP: 452 4.5.3 Your message has too many recipients / 452 Too many recipients received this hour

**Code:** `452 4.5.3 Too many recipients` · **Category:** Email / SMTP · **Seen on:** SMTP

The server limits how many recipients a single message or sender may have; yours exceeded it.

## Meaning

Providers cap recipients per message (Gmail 100 via SMTP, Microsoft 365 500) and per time window. Mass mailings must be split into batches or sent through an email service provider with proper list handling.

## Common causes

- Too many To/Cc/Bcc recipients in one message
- Per-hour or per-day recipient limit
- Using a personal mailbox for bulk mail
- Mailing list expanded to many addresses
- Limit on a shared hosting plan

## Quick fix

1. Send in batches (50-100 recipients) with pauses
2. Use an ESP (SES, SendGrid, Mailgun) for bulk mail
3. Check the provider's sending limits in their documentation

## Detailed fix by platform

### Postfix

1. `smtpd_recipient_limit = 1000` (inbound) and `default_destination_recipient_limit = 50` (outbound batches)

## How to diagnose

1. **Limit** — Provider's per-message cap?
2. **Window** — Hourly/daily quota?
3. **Method** — Mailbox or ESP?

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Source: [WhatIsMyError](https://whatismyerror.com/errors/email/452-4-5-3-too-many-recipients)