452: too many recipients in one message
Your server named more recipients in one transaction than GMX accepts, currently 20 per message, so the rest were deferred. Split the recipients into several transactions.
- GMX, WEB.DE
- Provider
- Temporary (4xx)
- Class
- Sources checked
- Author
At a glance
- Code
- 452
- Provider
- GMX, WEB.DE and mail.com
- Temporary or permanent
- TemporaryThe sending server keeps the message and tries again later.
- Who has to act
- The sender. The fix is on the sending side: your domain, your server or your list.
- What the server says
452 Too many recipients
What it means
GMX accepts at most 20 recipients (RCPT TO commands) for one MAIL FROM, according to case r0407, and at most 100 transactions per session. When a transaction goes past 20 recipients, GMX answers the extra ones with a temporary 452. Your server should close the connection, open it again and send the remaining recipients in a new transaction. Most servers split recipients this way by themselves once they meet a 452. GMX says the values may change and that it makes no exceptions or individual limits.
Common causes
- A message to a large group addresses more than 20 GMX recipients in one transaction.
- Your server is set to batch many recipients per message toward the same domain.
How to fix it
- 01Set your server to send at most 20 recipients per transaction to GMX domains.
- 02Keep each session under 100 transactions as well.
- 03Let the deferred recipients retry; they are delivered in a later transaction.
Sources
What this page rests on, checked on 20 Oct 2026. The explanation is ours; the reply text is the server's.
- GMX Postmaster case r0407: 452 Too many recipientspostmaster.gmx.net
Related codes
- 451Transaction limit per session reached.Your server sent more messages over one SMTP session than GMX allows, currently 100, so GMX deferred the next one. Close the session and open a new one.
- 452Insufficient system storage.The receiving server is short of storage or has hit a limit, such as the number of recipients in one message, and asks the sender to try again later.
452 at other providers
- 452Too many emails in one session.Your server sent more messages in one SMTP session than Xfinity accepts. Xfinity allows 1,000 emails per session, so the rest have to go in a new session.
- 452Too many recipients in one message.The message listed more recipients than Xfinity accepts at once. Xfinity allows 100 recipients per message, so a larger list has to be split.
- 452More than 100 recipients in one message.Mimecast accepts at most 100 recipients per message transaction and asks your server to send the rest in another batch. Most mail servers do this automatically.
- 452Hourly recipient limit reached.Your server sent more recipients to the company’s Cisco gateway this hour than its rate limit allows. The rest are deferred until the limit resets.
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