Configure SMTP in hMailServer
- Connect to hMailServer Administrator
- Expand Settings
- Expand Protocols
- Click on SMTP
- Maximum number of simultaneous connections (0 for unlimited): You can use this to reduce simultaneous SMTP connection to hMailServer. Reducing this to required value may also help against DOS attacks.
- Welcome message: This is the SMTP banner message which hMailServer uses in response to SMTP client’s connection response. SMTP Client issues further commands only after receiving this banner.
- Max message size (KB): hMailServer will reject messages larger than value specified here. Default value is 20MB. To set maximum message size to unlimited set it to zero.
Delivery of e-mail
Delivery of e-mail
- Number of retries: This value determines that how many times hMailServer should attempt to deliver email before returning the delivery notification failure message. Failed messages are held in delivery queue. The default value is 4. If you enter 10 here hMailServer will 11 times to deliver email before giving up.
- Minutes between every retry: This is the interval in minutes between each retry.
- Local host name: This is the host name of the hMailServer. This host name must resolve to the IP Address where hMailServer is running. You may setup up to 15 host names, but remember each host name must resolve to IP address of hMailServer. The host name is very critical when you are setting up live SMTP server to directly deliver emails to the destination servers by resolving their MX records. When sending SMTP server connects to another SMTP server to deliver email, the sending server first introduces itself by this host name to the receiving server. Here receiving server may try to resolve this host name supplied by sending server to it’s IP address from where it has received connection request. If the resolved IP doesn’t match with the IP address of the sending server then it may drop the connection.
By default if you do not configure SMTP relayer, hMailServer deliver emails directly to the destination servers by resolving their MX records. This is very useful and awesome feature while setting up live SMTP server. However in small setup where this kind of activity is not possible we can use SMTP relayer/smart host feature, so that hMailServer will deliver remote emails to this SMTP relayer which will then further deliver it to the destination servers. To configure SMTP relayer follow below steps:
- Remote host name: This is the host name of the SMTP server where hMailServer will deliver all remote emails. This should never be set to localhost which will cause trouble. hMailServer will try to connect itself which will create endless loop.
- Remote TCP/IP port: TCP/IP port of the SMTP relay server on which it listens.
- Server requires authentication: Select if your SMTP relay server requires authentication.
- User name: Specify username to authenticate with SMTP relay server.
- Password: Specify password of username provided in previous step.
- Use SSL: Select if SMTP relay server requires SSL connection.
- Allow plain text authentication: Enables plain text authentication if selected. Default is disabled.
- Allow empty sender address: hMailServer will allow emails with empty sender address. This should be enabled because there are many emails like read receipt which are sent from empty sender address.
- Allow incorrectly formatted line endings: Select to allow incorrectly formatted line endings. Generally spammers send incorrectly formatted emails but remember it may also be possible if there is any bug with SMTP client.
- Disconnect client after too many invalid commands: If enabled instructs hMailServer to drop connection forcefully if client issues too many invalid commands.
- Maximum number of invalid commands: Specifies number of invalid commands after which hMailServer will forcefully disconnect session with the client.
Deliver of e-mail
- Bind to local IP address: Specify which IP address should hMailServer use while connecting to remote SMTP servers, if you have multiple public IP addresses. If not specified, hMailServer will use Windows default
- Maximum number of recipients in batch: SMTP servers may reject email from hMailServer if there are too many recipients for a single mail. If hMailServer finds more number of recipients than the value specified here in a single email, then hMailServer will deliver to number of recipients specified by this setting in a single delivery and then disconnect and will again reconnect and continue with the rest of recipients.
- Add Delivered-To header: If enabled hMailServer will add Delivered-To header in all outgoing emails. This will contain recipient address given in the SMTP envelope during SMTP communication.
- Rule Loop limit: This will eliminate endless loops created due to global/user level rules.