Under normal circumstances, the antispam features will not impact mail delivery. However, the verification options may slow down the server, as they are resource intensive.
IMail Anti-Virus complements the antispam features of IMail Server. Connection filtering and verification for antispam are completed first, followed by the Anti-Virus scan. Then, the other antispam processes are initiated, beginning with content filtering. See also IMail Processing Order.
You can place the e-mail address or domain name, from which the message was sent, in the white list (trusted addresses) to always let messages from the e-mail address or domain name to be delivered.
If a small number of messages are being misidentified, you can use the antispamseeder.exe utility to add the messages to the antispam-table.txt file. This will increase the likelihood that similar messages will be correctly identified in the future.
If a large number of legitimate mail is being identified as spam, modify the Advanced Options on the Statistical Filter page. Begin by increasing An e-mail is spam when it's calculated probability exceeds option to 95%. If that has no effect, decrease The Probability a new word is spam option to 10%. See Also Advanced Statistical Filtering.
The black lists used are not maintained by Ipswitch, therefore we cannot verify their accuracy. Some black lists are updated more frequently than others, and contain more accurate information. You should be aware of this especially if you decide to configure your own black lists. For your convenience, IMail Server allows you to identify trusted black lists. These are black lists that you have tried and found to be accurate.
By default, messages that are identified as spam are forwarded to a mailbox called "bulk" within the root account. If you have changed the "Forward To" setting, on any of the antispam filter pages, then spam goes to the address that is entered in this field.
Only system and domain administrators can access the antispam tabs. System administrators have access to the server level DNS black lists and logging tabs. Host administrators have access to the host level DNS black lists, connection filtering, statistical filtering, phrase filtering, and Trusted DNS Black Lists.
The antispam tabs can be accessed from two places: the server level and host level. To access the server DNS Black Lists page, mouse over the IMail Administrator System tab, then click DNS Black Lists. The DNS Black Lists page opens.
To access domain (host) level settings, click the IMail Administrator AntiSpam tab. The AntiSpam Settings page opens. The domain level antispam options are displayed on the Domain Level Spam Filtering page.
Most mailing list subscriptions will not be identified as spam. However, to ensure that mailing list messages are not identified as spam, place the domain name from which the mailing list is sent in the Trusted Addresses list. For more information, see Creating Trusted DNS Black Lists.
If you do not trust the domain, you can create a host rule to send the message to a folder for the user (for example, spam), and the user can create a user rule that puts the message in his/her Inbox. For more information, see Using Delivery Rules to Filter Spam.
Yes. IMail Server processes mail from IMail Web Messaging in the same way it processes all other mail.
The file, that ships with the product, is appropriate for most users. However, you may need to alter this file if we have identified words as spam that you do not consider to be spam, or vice versa. For example, the word "mortgage" is identified as spam because in our tests, it occurred 364 times in non-spam, and 7516 times in spam. However, at financial institutions, the word "mortgage" is a non-spam word that occurs frequently. In this case, you need to alter the antispam-table.txt file so that statistical filtering recognizes the word "mortgage" as non-spam. For more information, see Customizing a Host's Antispam-table.txt file.
The antispam engine automatically filters mail from all users who are not authenticated. If you are concerned about your authenticated users sending spam, you can prevent this by selecting the Enable content filtering for authenticated users option located on the Domain Level Spam Filtering page. By doing this, outgoing mail from authenticated users is always evaluated to determine whether it is spam.
Authenticated users are users who have SMTP Authentication enabled on their e-mail client or users who send mail from IMail Web Messaging. By default, IMail Server forces users to authenticate, unless you select another option such as Relay Mail for Anyone or Relay Mail for Addresses in the Mail Relay Settings located under Services tab > SMTP. This means that every time a user connects to the IMail Server, he/she must enter his/her user ID and password.
Each location serves a different purpose. The phrase list filters the domain name as it appears in normal text in the body of an e-mail message. The URL Domain Black List will filter the domain name if it appears as a link in HTML code within a message, specifically within HREF and IMG SRC tags.