Spam question

[Kit]

I have a question about whitelisting and blacklisting. I don’t have an acct (yet) and use Apple Mail as opposed to accessing my email via webmail. So can I still send spam mail (and good mail) to Fastmail to be learned from Mail or does that have to be done via the web interface?

Thanks,

Kit

[n5bb]

Hi, Kit. To use Fastmail spam filtering features, you need to get a paid account. Free accounts have no spam filter.

Fastmail has several ways of reducing spam.

• Incoming connections from insecure email servers are refused before messages are even accepted. In some cases, connections are delayed (greylisting), which can reject some spam sources but should only delay good messages the first time the server attempts a connection.
• Paid accounts also have a spam filter, which uses SpamAssassin spam filtering along with local Fastmail tweaks and a Bayes filter component. You can set the spam score which triggers a message to be treated as spam and be automatically filed into the Junk Mail folder. You can also set another threshold for deleting messages with high spam scores. Fastmail provides presets for these settings, but allows you to customize them.
• Many other features can also be customized in Fastmail. This is done through the web interface (although you can use an email client such as Mail to send and read your mail).
• Bayes filtering allows the spam filter to treat some messages as less likely to be spam (because you have previously reported similar messages as not-spam), while other messages are treated as more likely to be spam (because you previously reported similar messages as spam).
• Fastmail has a default global Bayes system (based on a large sample of email from all accounts), but it's much better to switch to the user Bayes system (based on you individual spam experience and reports). To use this user Bayes feature, you need to initially report at least 200 spam and 200 non-spam messages, then you should continue to report spam and non-spam to train the system as your message experience changes over time.
• When using Fastmail from the web interface, you can just use the Report spam or Report non-spam buttons. But you obviously can't use these from your email client.
  • Instead, all you need to do is to specify certain folders to be used for automatic spam reporting (normally just the Junk Mail folder, although you could specify more than one folder) and other folders to be used for automatic non-spam reporting (such as Inbox or folders where you file good messages).
  • These folders need to be synchronized between your email client (Mail) and the Fastmail IMAP server. So you need to set up your client for IMAP access to Fastmail, then subscribe to all folders you wish to synchronize. You can have local folders on your client which are not subscribed, but contents of those folders will not be known to Fastmail.
  • At the Fastmail web interface, you can edit your IMAP server folder names and other settings (such as automatic spam classification). You need to set up some folders (such as Junk Mail) for automatic spam reporting, and other folders (such as Inbox and other good message storage folders) for non-spam reporting. Once per day (typically overnight in New York City, the location of the Fastmail email servers), messages in those automatic reporting folders on the Fastmail IMAP server will be used for changing your user Bayes spam classification.
  • If you make a mistake in putting a message in a folder for spam classification, don't worry. You can just move the message to the correct reporting folder, and within 24 hours it will be correctly reported (correcting the previous spam classification).
• You can also create message rules at the Fastmail web interface for rejecting certain messages, forwarding messages, vacation messages, and filing messages into folders. These actions will take place whether or not your email client is online, and you can easily switch back and forth between webmail and the email client with no issues.
• You can whitelist certain email addresses so that messages sent from those addresses are not accidentally classified as spam. This is done by placing the addresses in the online Fastmail Address Book. Messages will always bypass the Junk Mail folder when they are whitelisted using the Address Book, as opposed to the biasing of the spam score discussed earlier (which is not a certain situation, since it looks at complex and changing spam content rather than just addresses). You can also whitelist a complete domain by using an address such as *@gmail.com. If you have a large address list already on your email client, you can export it and then import it into your Fastmail address book. At this time this is a manual operation, since there are a number of address listing formats and some cleanup might be needed. But there are semiautomatic address book synchronization methods appearing -- see this EMD thread:
  Addressbook sync service available for testing

Bill

[Kit]

Thanks so much for your help. It’s the Bayesian filters that I’m most interested in as I currently use SpamAssassin with my current ISP and it isn’t working that well despite a spam setting of 2 (5 is normal). I still get 100-200 spams a day with SpamAssassin. .

Thanks,

Kit

[n5bb]

Do you own your own domain(s)? Fastmail has very flexible services for dealing with the DNS management, SPF, CSV, and other issues. All of this requires an Enhanced account, but all of the advanced features are included with no other charges. You can use this one account with up to 50 of your own domains and up to 500 domain aliases (or subdomains).

The worst case situation is to receive most of your email by forwarding to Fastmail and not configuring user Bayes filters and not using address book whitelisting. This puts all of the spam filtering job on SpamAssassin, which does a good job but will always have a possibility of false positives unless you leave the spam filter threshold rather high -- this of course allows a few spam to still arrive at your Inbox.

• Changing to using addresses at a Fastmail domain (or your own domain with MX set to the Fastmail incoming servers) dramatically improves the situation. Incoming connection attempts are refused (or greylisted with an initial delay) from suspicious sending servers. Forwarding tends to cripple various email security and reliability features, so it's best to limit use of forwarding services.
• Training the per-user Bayes filter gives another kick in spam filtering performance. Now you can increase the chance that the common spam your receive will be filtered out.
• Adding reject rules in the Sieve-based forms system is useful if you get a lot of spam with characteristics you can see in the full headers or body which are repeatable. Some spammers produce messages which are very close to common commercial messages, and it's difficult to filter these unless you filter based on their domain name, address in the body, or other features.
• Then I think the last key technique is to force yourself to use address book whitelisting. If you can get all of your common correspondents (personal and business) into your online Fastmail address book (or add their domains using *@domain.xxx), then you can be assured that mail from those senders will never end up in Junk Mail. So you can get aggressive with your spam thresholds without fear of losing ham (good messages) unless you have a sender who likes to change their address without telling you in advance. I still occasionally get a bank or other business correspondent who for some reason changes their address without warning. If they just change the user part (before the @) it's not a big problem, since you can whitelist their whole domain with *@domain.xxx). But if they change their domain or subdomain (as in xxx@sub1.domain.yyy to xxx@sub2.domain.yyy), then you will have to add the new full domain (*@sub2.domain.yyy) to the address book.

I hope I'm not overloading you! But with that level of spam load you need all the spam-fighting features you can get! The good news is that Fastmail gives you the flexibility to control most of these features yourself, rather than be limited to some mostly fixed spam filtering standard setup.

Bill