Protecting Mailboxes From Spam

Once you start using e-mail, you are likely to start receiving lots of messages that, as you may think, have gotten to your mailbox by mistake because you do not know the sender, and you personally did not subscribe to that newsletter or requested the product or service that these messages advertise. These unwanted e-mail messages are called unsolicited commercial e-mail, however, most people prefer calling them mass mailing, bulk mail, junk mail or spam.

Aside from advertising, you can receive e-mail messages that falsely claim to be from legitimate enterprises, such as banks or Internet auctions. These messages can say, for example, that your account information needs to be updated, and to do that, you need to click the link they provide in the message. The link takes you to a fake Web site, which had been set up by fraudsters to steal your sensitive information, such as login names, passwords, credit card and bank account numbers. This is a type of scam called phishing.

To avoid receiving such undesirable correspondence, do not publish your new personal e-mail address on Internet message boards and forums because spammers gather e-mail addresses from the Internet. Thus, your e-mail address may get on their lists and you will receive lots of spam. If you need to publish your e-mail address, create a disposable e-mail address - e-mail alias - for your mailbox, and publish it instead. All messages sent to the e-mail alias will come into your mailbox. Once you start getting spam, remove that alias and create another one. If you have a mailbox at another domain or mail server, you may want to set up a disposable e-mail forwarder.

We advise that you do not read spam e-mails when you receive them, just delete them at once. Even if you have read them, do not respond to them and do not click those "click here to unsubscribe" URLs: spammers will then know that your e-mail address is valid and you will get even more spam. Spam is there because people buy the products or services advertised in spam. So, if you do not like spam, do not support spammers — do not buy from them.

To switch on spam filtering for a mailbox:

1. On your Home page, click the domain name you need.
2. Click the Mail icon in the Services group.
3. Click the e-mail address you need.
4. Make sure that Spam Filter is enabled: see whether the Spam Filter status shows On in the Info group. If it shows Off, ask your service provider to enable the spam filtering.
5. Click Spam Filter.
6. Select Enable spam filtering checkbox.
7. Click OK.
8. Click Up Level to return to the mailbox management page.

Now all the incoming mail will be filtered on the server side. By default, spam filter does not delete spam mail, it only adds the "X-Spam-Flag: YES" and "X-Spam-Status: Yes" headers to the message, and "*****SPAM*****" text string to the beginning of Subject line of each message recognized as spam. These settings are fine if you prefer to filter mail with a filtering program installed on your local computer – once mail has been retrieved from your mailbox.

If you rely entirely on the Plesk server's spam filter, you may configure it so as to automatically delete the suspicious messages as they come. To configure the spam filter, follow the instructions below.

To configure the spam filter for a mailbox:

1. On your Home page, click the domain name you need.
2. Click the Mail icon in the Services group.
3. Click the e-mail address you need.
4. Click Spam Filter in the Tools group. Configure the following settings as desired:
   • Use server wide settings. Select this option if your provider or server administrator has prepared black and/or white lists of e-mail addresses that you would like to use together with your own restrictions. Black list, shown under Black list group, includes e-mail addresses of spammers, and White list, shown under White list group, includes e-mail addresses of trustworthy correspondents or entities. If the Use server wide settings check box is grayed out, i.e. not selectable, this means that there are no preconfigured spam filter settings on the server.
   • Hits required for spam. This setting adjusts spam filter sensitivity. SpamAssassin performs a number of different tests on contents and subject line of each message. As a result, each message scores a number of points. The higher the number, the more likely a message is spam. For example, a message containing the text string "BUY VIAGRA AT LOW PRICE!!!" in Subject line and message body scores 8.3 points. By default, the filter sensitivity is set so that all messages that score 7 or more points are classified as spam.
   • If you receive lots of spam messages with the current setting, to make filter more sensitive, try setting a lesser value in the Hits required for spam box; for example, 6.
   • If you are missing your e-mails because your spam filter thinks they are junk, try reducing filter sensitivity by setting a higher value in the Hits required for spam box.

     Note: To further improve spam filter accuracy, you may want to train your spam filter on e-mail messages you receive (see the instructions on improving accuracy of spam detection below).

   • What to do with spam mail. If you are sure that your spam filter is accurate, you may want to set the filter to automatically delete all incoming messages recognized as spam. To do this, select the Delete option. If you wish to filter mail with the software on your local computer, select the Mark as spam and store in mailbox option, and then specify how spam filter should mark the messages recognized as spam. "X-Spam-Flag: YES" and "X-Spam-Status: Yes" headers are added to the message source by default, and if you want, the spam filter will also include a specific text string to the beginning of Subject line.
5. To save your changes, click OK.
6. If you do not want to receive e-mail from specific senders, add their e-mail addresses to the spam filter's black list.
   • To add an entry to the black list, under Black list group, type an e-mail address into the E-mail pattern box. For example: address@spammers.net, *@spammers.net. An asterisk (*) means any combination of symbols. Click Add.
   • To remove an entry from the black list, select it and click Remove.
7. If you want to be sure that you will not miss e-mail from specific senders, add their e-mail addresses to the spam filter's white list.
   • To add an entry to the white list, under White list group, type an e-mail address into the E-mail pattern box. For example: address@mycompany.com, *@mycompany.com. An asterisk (*) means any combination of symbols. Click Add.
   • To remove an entry from the black list, select it and click Remove.
8. If you want spam filter to consider some networks to be trusted:
   • Select the Trusted Networks tab.
   • To add an entry to the list, enter a network address into the fields next to Network/Mask and click Add.

     A network is specified by its starting IP address in the first four fields of the Network/Mask field group. The fifth field is for specifying network mask. It should be a number ranging from 1 to 32, which shows how many higher bits set to '1' the mask contains. For example, for the mask 255.255.255.0 you should specify 24 as the fifth parameter.

   • To remove an entry from the list, select a network and click Remove.

     The relay hosts on trusted networks are considered not to be potentially operated by spammers, open relays, or open proxies. A trusted host could conceivably relay spam, but will not originate it, and will not forge header data. DNS blacklist checks will never query for hosts on these networks.

You can improve accuracy of spam detection by training the spam filter on the e-mail messages that you have in your mailbox.

To improve accuracy of spam detection:

1. On your Home page, click the domain name you need.
2. Click the Mail icon in the Services group.
3. Click the e-mail address you need.
4. Click the Spam Filter icon in the Tools group.
5. Click the Training icon in the Tools group.

   All e-mail messages you have in your mailbox are presented on the screen. Each message is accompanied by an icon in the left column, which tells if a message is recognized as spam - , non-spam - , or not recognized at all - . If you have already trained your spam filter on a message and the results were recorded in the spam filter's database, an icon is shown in the right column.

6. Train the spam filter.

   In most cases, you can tell if a message is spam by looking at its subject line and sender's name. If they do not give you any clue, try looking inside the message using your e-mail program or webmail interface.

   • To mark a message as spam, select the corresponding check box and click 'It's Spam!'.
   • To mark a message as not spam, select the corresponding check box and click 'It's Not Spam'.
   • To remove any information on a given message from the spam filter database, select the corresponding check box and click 'Forget It'.
7. Once finished with training, you can remove spam e-mails from your mailbox using your e-mail program or Webmail interface.

If you have accidentally made your spam filter learn a great number of spam e-mails as non-spam or vice versa, your spam filter will likely produce incorrect results. In this case, clear the spam filter's database and then repeat training.

To clear spam filter's database:

1. On your Home page, click the domain name you need.
2. Click the Mail icon in the Services group.
3. Click the e-mail address you need.
4. Click the Spam Filter icon in the Tools group.
5. Click the Training icon in the Tools group.
6. Click the Clear button.

To switch off spam filtering for a mailbox:

1. On your Home page, click the domain name you need.
2. Click the Mail icon in the Services group.
3. Click the e-mail address you need.
4. Click Spam Filter in the Tools group, then clear the Enable spam filtering check box, click OK and click Up Level.