Comodo KoruMail

SMTP server banner text

The welcome message shown on the server after successfully connecting to KoruMail port 25.

Maximum acceptable mail size (MB)

 The maximum permitted size of a single email + attachments. The default value is 20 MB.

Activate DoS protection

A DoS (Denial of Service) attack occurs when a malicious actor tries to overload your mail server by bombarding it with unsolicited mail. DoS protection implements limits to help ensure your servers are not brought to a standstill by such attacks.

Enable SMTP submission port

 If enabled, KoruMail will not accept outgoing messages from unauthenticated sources, thus helping to protect your network and users from spam emails.

 Enable SPF Recommended value: 3

 SPF (Sender Policy Framework) is a standard designed to block the forgery of sender addresses.

SPF values

1. Just add received-SPF header

2. Return temporary failure in DNS query error

3. If SPF result fails (ban) then reject it (recommended)

4. If SPF result is softfail then reject it

5. If SPF result neutral then reject it

6. If SPF result is not passed then reject it
   

You can disable SPF by selecting '0' from the list. If the check box 'Only for hosted domains' is selected, then the SPF check will be performed for outgoing mails for domains that are hosted in the network.

Enable SPF Recommended value: 3

Sender IP based location detection. This should be enabled here in order to activate the geo location restriction settings in the incoming profiles. Mails from restricted countries list will be rejected.

Minimum number of filter processors

The least filter processes that the filtering engine should use. Filter processors are threads used to scan and handle mail.

• Fewer processors = Lower resource overhead / slower performance

Maximum number of filter processors

The most filter processes that the filtering engine should use. Filter processors are threads used to scan and handle mail.

• More processors = Higher resource overhead / better performance

Maximum number of recipients per SMTP transaction

The highest number of mailboxes to which KoruMail will forward mail per transaction.

Incoming SMTP session timeout (seconds)

Timeout duration of each SMTP session.

RBL Timeout (seconds)

If this time is exceeded, the RBL query is canceled and next filter is applied to the e-mail.

Early talker drop time (seconds)

After a client makes a TCP connection, SMTP servers will wait a for short time before sending a greeting message. The client replies with a HELO or a EHLO response.

If the server receives the response before sending the greeting, then the client could be serving spam. The waiting time before sending the greeting is called 'Early talker drop time'.

We recommend you leave the setting at the default.

Reject invalid addresses

If enabled, incoming mails with invalid address will be rejected

Queue life time (hour)

Enter the number of hours that a mail can be queued for delivery before it is bounced.

Enable tarpitting

Tarpitting helps thwart spammers by slowing the transmission of bulk emails. Tarpits slow communication times with spam servers when they send mail to several of your recipients during one session.

Spammers may stop sending emails to your server if the response to their requests is very slow.

Tarpit count

Tarpitting will become active if the number of recipients exceeds the Tarpit count.

Tarpit delay (second)

The number of seconds that Tarpitting will delay the transmission response

Maximum number of SMTP sessions

Maximum number of simultaneous SMTP sessions.

Maximum number of concurrent mail delivery

Maximum number of simultaneous outgoing messages that can be sent.

Main Filter engine log level

Select the level of main filtering engine event that should be logged. Selecting 'Debug' will log all the levels.