5.5.3
Enhanced Status Code 5.5.3: Too Many Recipients
Permanent failure
Medium severity
Protocol
RFC 3463
What it means
Enhanced Status Code 5.5.3 means “Too Many Recipients.” Your email attempted to include more recipients than the receiving server allows in a single message. Most servers limit recipients per message to 50-500. Split large recipient lists across multiple messages.
At a glance
Code5.5.3
Bounce typeHard (permanent)
SeverityMedium
CategoryProtocol
What to doSuppress the address; do not retry
StandardRFC 3463
550 5.5.3 Too many recipients for this message; the per-message recipient limit was exceeded.What does 5.5.3 mean?
Enhanced status code 5.5.3 means you attempted to send an email with more recipients (RCPT TO commands) than the receiving server allows in a single SMTP transaction. Most mail servers impose per-message recipient limits to prevent abuse.
Gmail allows up to 100 recipients per message for external sends. Microsoft 365 allows 500 recipients per message. However, for bulk sending, you should always send to individual recipients or small groups rather than adding hundreds of recipients to a single message. Using individual sends also allows personalization and proper tracking.
How 5.5.3 plays out
Your server attempts delivery
The recipient server returns a permanent
5.5.3 rejectionThis is a hard bounce: the message will not be accepted as sent
Suppress the address and fix the root cause before resending
Where 5.5.3 sits: soft vs hard bounce
| Soft bounce (4xx) | Hard bounce (5xx) | |
|---|---|---|
| Nature | Temporary | Permanent |
| SMTP class | 4xx | 5xx |
| What to do | Let it retry | Suppress the address |
| Recoverable? | Often | No |
| 5.5.3 is | ✓ this code |
Common causes of 5.5.3
- Too many recipients in a single email (To, CC, or BCC)
- Bulk sending script adding too many RCPT TO commands per transaction
- Mailing list software not splitting large lists into batches
How to fix 5.5.3
- Split large recipient lists into batches that comply with the server limit
- Send individual emails to each recipient (preferred for bulk sending)
- Check the receiving server limit (typically 50-500 per message)
- Use proper email marketing tools that handle batching automatically
Frequently asked questions
What does error 5.5.3 "too many recipients" mean?
Error 5.5.3 (or 452 4.5.3) means your email included more recipients than the mail server allows in a single message. Every mail server has a maximum recipient limit per message, which includes all To, Cc, and Bcc recipients combined. Microsoft 365 allows up to 500 recipients per message, Gmail limits personal accounts to 500 recipients per day, and other providers have their own thresholds. The message is rejected before delivery to any recipient.
How many recipients can I include in one email?
The limit depends on your email provider. Gmail (personal) allows up to 500 recipients per day and per message. Google Workspace allows up to 2,000 per day. Microsoft 365 / Exchange Online allows 500 recipients per message. On-premises Exchange defaults vary and can be configured by the administrator. If you need to reach more recipients, split your list into smaller batches or use a dedicated email marketing platform like Mailchimp or SendGrid that handles batching automatically.
How do I fix the "too many recipients" SMTP error?
Split your recipient list into smaller groups; for most providers, keep each batch under 100 recipients per message to be safe. Use BCC for large distributions to avoid exposing all addresses. Space out batches with delays (e.g., 1-2 minutes between sends) to avoid triggering rate limits. For regular large-volume sends, switch to a dedicated bulk email service that manages recipient limits, throttling, and compliance automatically. Server administrators can also increase the MaxRecipientsPerMessage setting if appropriate.
Does the recipient limit include BCC addresses?
Yes, the recipient limit includes all addresses in To, Cc, and BCC fields combined. Even though BCC recipients are hidden from other recipients, they still count toward the server's per-message recipient limit. A message with 10 To addresses, 5 Cc addresses, and 490 BCC addresses totals 505 recipients and would exceed a 500-recipient limit. Always count all recipient fields when planning large sends.
Related bounce codes
Sources & further reading
Reviewed by Jennifer Jackson, Email Deliverability Analyst · June 2026
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