Spam-filters calculate “spam score” to detect junk mail.
To determine whether a given e-mail is spam or not most spam filters consider a number of different attributes, such as content, length, percentage of text, use of images, number of recipients, headers etc. Usually they calculate the so-called “spam score” for every e-mail which passes the server.
If the mail’s score exceeds a certain threshold the mail is blocked and lands in the spam folder. The level where the threshold is set is defined by the mail server configuration. By default, this spam filter flags messages with a score greater than 5 as spam.
Spam filters aren’t perfect.
Over the last years the efficiency of spam filters used by e-mail software clients and web-based e-mail-services has improved dramatically. However, since the strength level of anti-spam-algorithms has increased, it’s inevitable that also more legitimate e-mails don’t get through them. The result is that these filters, in order to block a good percentage of spam mails, block a good percentage of “suspicious” — in reality non-spam — messages as well.
Newsletters remain important, RSS-feeds haven’t made the breakthrough yet.
In its recent usability study Nielsen Norman Group found out that news feeds are definitely not for everybody, and they’re not a replacement for email newsletters. Apparently, “feeds are a cold medium in comparison with email newsletters. Feeds don’t form the same relationship between company and customers that a good newsletter can build.
Given that newsletters are a warmer and much more powerful medium, it is probably best for most companies to encourage newsletter subscriptions and promote them over feeds on their website.” Therefore it’s important to be aware of some sound techniques to pass through anti-spam-filters and thus guarantee a good newsletter delivery.
E-mail delivery is tricky.
The fact is that in most cases you never really know whether your first e-mail addressed to someone who doesn’t know you and/or isn’t expecting your e-mail will come through mail filters. And since the recipient doesn’t expect your mail he/she won’t be able to take it into consideration. Therefore it’s necessary to be aware of some techniques to ensure the delivery of your e-mails.