SMTP Session Limits

From ASSPSMTP

On This Page 1 How It Works 2 Details 3 SMTP Session Limits FAQs 4 SMTP Session Limits Configuration

How It Works

Details

SMTP Session Limits FAQs

SMTP Session Limits Configuration

based upon version 1.3.5(9.18)

Do Deny SMTP Connections from IP's (Strictly) (DoDenyConnect)

If activated, the IP is checked against Deny SMTP Connections from these IP's Strict.

0 = disabled, 1 = block, 2 = monitor.

Deny SMTP Connections from these IP's Strictly* (denySMTPConnectionsFromAlways)

Manually maintained list of IP's which should strictly be denied SMTP access. Connection will be denied right away, before the body and header is downloaded.

Maximum Errors Per Session (MaxErrors)

The maximum number of SMTP session errorsSMTP session errors encountered before the connection is dropped.

Maximum Sessions (maxSMTPSessions)

The maximum number of simultaneous SMTP sessions. This can prevent server overloading and DoS attacks. 64 simultaneous sessions are typically enough. No entry or zero means no limit.

Maximum Sessions Per IP Address (maxSMTPipSessions)

The maximum number of SMTP sessions allowed per IP address. Use this setting to prevent server overloading and DoS attacks. 5 sessions are typically enough. If left blank or set to 0 there is no limit imposed by ASSP. ISP/Secondary MX Servers and Accept All Mail matches are excluded from SMTP session limiting.

Check Frequency - Maximum Connections Per IP (DoFrequencyIP)

0 = disabled, 1 = block, 2 = monitor, 3 = score.

Maximum Frequency of Connections Per IP (maxSMTPipConnects)

The maximum number of SMTP connections an IP Address can make during the IP Address Frequency Duration. If a server makes more than this many connections to ASSP within the IP Address Frequency Duration it will be banned from future connections until the IP Address Frequency Expiration is reached. This can be used to prevent server overloading and DoS attacks. 10 connections are typically enough. If left blank or 0, there is no limit imposed by ASSP. IP's in noPB, noDelay, acceptAllMail, ispip, whiteListedIPs, noProcessingIPs, PB-whitebox are excluded from SMTP session limiting, whitelisted and noprocessing addresses are honored

Maximum Frequency of Connections Per IP Duration (maxSMTPipDuration)

The window (in seconds) during which the IP Frequency (see above for more details) will be scrutinized for each IP. The default is 90 seconds.

Expiration of Maximum Frequency (maxSMTPipExpiration)

The number of seconds that must pass before an IP address blocked by the IP Address Frequency setting is allowed to connect again. The default is 7200 (seconds) .

Check Number of IP's Per Domain (DoDomainIP)

0 = disabled, 1 = block, 2 = monitor, 3 = score.

Limit Number of IP's Per Domain (maxSMTPdomainIP)

The number of IP(subnet) switches a domain may have during the Limit Different IP's Per Domain Expiration. If a domain switches more often than this it will be banned from future connections until the Expiration is reached. This can be used to prevent server overloading and DoS attacks. 10 connections are typically enough. If left blank or 0, there is no limit imposed by ASSP. IP's in noPB, noDelay, acceptAllMail, ispip, whiteListedIPs, noProcessingIPs, PB-whitebox are excluded, whitelisted and noprocessing addresses are honored.

Expiration of Limit Number (maxSMTPdomainIPExpiration)

The number of seconds that must pass before a domain blocked by the Limit Subnet IP's Per Domain setting (see above for more details) is allowed to connect again. The default is 7200 (seconds).

Do Not Limit Different IP's For These Domains* (maxSMTPdomainIPWL)

This prevents specific domains from limiting. For example: yahoo.com|hotmail.com|gmail.com

SMTP Idle Timeout (smtpIdleTimeout)

The number of seconds a session is allowed to be idle before being forcibly disconnected. The default is 180 seconds. No limit is imposed by ASSP if the field is left blank or set to 0.