SMTP Service Configuration

SMTP service is the major service of EmailArchitect server. It sends/receives email with remote SMTP server or email client based on SMTP protocol. SMTP uses 25 port to accept the email from remote SMTP server or email client. Therefore, you MUST open 25 port for incoming connection; otherwise you cannot receive email from outside domains.

General Settings

IP Address: By default, SMTP/POP3/IMAP4/Remote Object Call services listen on all IP addresses of the server. In most case, you do not have to change this setting. To make the service to listen on specified IP address, you can change the IP Address field like this:
If you only need this service listen on 192.168.0.1,
then just input 192.168.0.1 to IP address.

If you want to bind multiple addresses in this service.

192.168.0.1
192.168.0.2
192.168.0.3
Then input: 192.168.0.1, 192.168.0.2, 192.168.0.3

If you want to bind multiple addresses with different port

192.168.0.1 with 25 port
192.168.0.2 with 25 port
192.168.0.3 with 587 port
Then input: 192.168.0.1 25, 192.168.0.2 25, 192.168.0.3 587

If you also use * to listen on all IP addresses on specified port

E.g. you want to your SMTP service to accept connection on both 25 and 587 ports.
Then input: * 25, * 587
Important Notice: Please have your SMTP service always listens on 25 port. 25 is a standard port to accept outside email. If SMTP service does not listen on 25 port, the service cannot receive email from outside domain.

Port: Tcp port to accept the SMTP connection, default is 25. If you want to bind SMTP service to both 25 and 587 ports, please input: * 25, * 587 in IP address.

SSL IP Address: By default, SMTP/POP3/IMAP4/Remote Object Call services listen on all IP addresses of the server. In most case, you do not have to change this setting. To make the service to listen on specified IP address, you can change the IP Address field like this:
If you only need this service listen on 192.168.0.1,
then just input 192.168.0.1 to IP address.

If you want to bind multiple addresses in this service.

192.168.0.1
192.168.0.2
192.168.0.3
Then input: 192.168.0.1, 192.168.0.2, 192.168.0.3

SSL Port: Tcp port to accept the SMTP SSL connection, default is 465.

SSL enabled: Enable or disable SSL connection.

Require SSL connection with user authentication: If this option is enabled, the user MUST set SSL connection in the email client, otherwise user authentication will be denied.

STARTTLS Command: If this option is enabled, remote SMTP server or email client can switch connection from normal TCP connection to SSL connection in SMTP connection.

Allow MAIL FROM: <>: Allows null sender in "MAIL FROM" command. Note: most non-delivery reports use null sender.

Connection Control

Connection control is to block connection to SMTP server from specific subnets or IP addresses. EmailArchitect Email server offers you the following 2 options (Permit List and Deny List):

Only the IP addresses in the list. Only the IP addresses is matched to an item in the list, the user can connect to the SMTP server. (If you selected this option, outside SMTP server may not send email to your SMTP server)
All except the IP addresses in the list. If the IP addresses is matched to an item in the list, the user cannot connect to the SMTP server. (This option is recommended)

Wildcard character (*) or CDIR syntax are available to identify a group of IP addresses. E.g. 192.168.0.* or 202.*. CDIR syntax: E.g. 192.168.0.1/16 represents a group IP addresses from 192.168.0.1~192.168.255.255.

Relay Restriction

Relay Restriction is to restrict anonymous user from relay message from the SMTP server to the outside domains. EmailArchitect Email server offers you the following 2 options:

Only the IP addresses in the list. (This option is recommended)
All except the IP addresses in the list. (If you selected this option, spammers may use your SMTP server to relay junk emails.)

Messages

Limit message size to: If the email size is out of the limit, the email will be rejected.

Limit number of messages per connection to: After a connection is accepted, the maximum emails of remote SMTP server or email client can send to your SMTP server.

Limit number of recipients per message to: Maximum recipients count in each message.

Delivery

EHLO: Always use EHLO in SMTP command, but some older SMTP servers do not accept this command.

HELO/EHLO Domain

A HELO command with a domain name is sent to remote SMTP server to identify current server while local SMTP service is relaying an email to a remote recipient. If no domain is specified in this option, default value is the sender's email address domain.

Some of SMTP server performs DNS Reverse to check if the domain is complied with IP address of current server. Therefore, assigning a valid internet domain resolved to current server is recommended.

Relay Message by Remote Host

Normally, you need not to input any value for this option. The local EmailArchitect Server would relay emails to remote user directly. But if you want to use another SMTP server to relay all remote emails, then you should input the IP address or domain name of the SMTP server to this option.

If the SMTP server specified in "Relay Message by Remote Host" option requires ESMTP authentication, then you should assign corresponding value to "User Name for ESMTP Authentication" and "Password for ESMTP Authentication" options.

Remote Port: The remote SMTP server port, the default value is 25. Do not change this value in most cases.

Using TLS if possible: If recipient's SMTP server supports SSL connection, then use SSL connection instead of TCP connection.

Local Address: SMTP service uses the primary IP address to send remote email, but you can specify an IP address to SMTP service -> Delivery -> Local Address, then SMTP service will bind this IP address to send remote email. If you want to set specified domain binding with specified IP address, you set it like this: emailarchitect.com:192.168.0.1, 192.168.0.2 then email from emailarchitect.com uses 192.168.0.1, and other domains use 192.168.0.2. Import Notice: you should bind the IP address to a valid internet IP address but not local LAN IP address.

Retry interval (seconds):: Retry interval for undeliverable message (temporal error). If the email has a permanent error such as "no such user", SMTP service will not retry it.

Expiration timeout (seconds):: If the message could not be delivered to specified recipient in the time, SMTP service would send a failure report to sender. If this value is set to 0, SMTP service will send the non-delivery report back to sender immediately without retry.

Concurrent Outbound Connections Limit: For example: if you input: yahoo.com:10, hotmail:5, *:3, that means SMTP Service does not generate more than 10 concurrent connections to yahoo.com, 5 concurrent connections to hotmail.com and 3 connections to other domains. all:100 means not generating more than 100 concurrent connections for all domains. Note: you must separate multiple rules by line-break.

Outbound Traffic Throttling: For example: if you input: yahoo.com:1000, hotmail:500, *:800, that means in the specified minutes SMTP Service does not send more than 1000 emails to yahoo.com, 500 emails to hotmail.com and 800 emails to other domains. all:10000 means not sending more than 10000 emails in specified minutes for all domains. Note: you must separate multiple rules by line-break. If you set interval to "0", then throttling limit is disabled.

EmailArchitect Server Website
EmailArchitect Server Community