簡介
本文檔介紹由於思科郵件安全裝置(ESA)上的大報頭而被拒絕和退回的郵件。
「552 #5.3.4郵件報頭大小超過限制」的退回郵件
當主機嘗試傳送帶有大報頭的郵件時，ESA可能會拒絕該郵件。終端使用者可能會看到以下錯誤消息之一：
"552 #5.3.4 message header size exceeds limit"
"500 #5.5.1 command not recognized"
"421 Exceeded bad SMTP command limit"
在其他情況下，主機可能會繼續重試同一消息。
訊息標頭有1000行的限制。當報頭長度超過1000行時，ESA將「552 #5.3.4消息報頭大小超過限制」消息傳送到傳送主機。
某些主機可能會忽略此消息並繼續傳送資料。ESA將此資料解釋為SMTP命令，並返回每行「500 #5.5.1命令無法辨識」。
在超出了4個錯誤SMTP命令的限制後，ESA返回消息「421超出錯誤SMTP命令限制」，並丟棄連線。
此設定只能在CLI上變更：
myesa.local> listenerconfig
Currently configured listeners:
1. listener_myesa.local (on Management, 192.168.0.199) SMTP TCP Port 25 Public
Choose the operation you want to perform:
- NEW - Create a new listener.
- EDIT - Modify a listener.
- DELETE - Remove a listener.
- SETUP - Change global settings.
[]> setup
Enter the global limit for concurrent connections to be allowed across
all listeners.
[50]>
Listener istener_myesa.local Policy $TRUSTED max concurrency value of 300
will be limited to 50 by this concurrency setting.
Enter the global limit for concurrent TLS connections to be allowed across
all listeners.
[100]>
Concurrent TLS connections value of 100 will be limited to 50 by the global
limit for concurrent connections.
Enter the maximum number of message header lines. 0 indicates no limit.
[1000]>
Enter the rate at which injection control counters are reset.
[1h]>
Enter the timeout for unsuccessful inbound connections.
[5m]>
Enter the maximum connection time for inbound connections.
[15m]>
What hostname should Received: headers be stamped with?
1. The hostname of the Virtual Gateway(tm) used for delivering the message
2. The hostname of the interface the message is received on
[2]>
The system will always add a Message-ID header to outgoing messages that don't
already have one. Would you like to do the same for incoming messages? (Not
recommended.) [N]>
By default connections with a HAT REJECT policy will be closed with a banner
message at the start of the SMTP conversation. Would you like to do the rejection
at the message recipient level instead for more
detailed logging of rejected mail? [N]>
如果進行了任何更改或更新，請返回主CLI提示符並運行commit以儲存和實施更改。
相關資訊
意見