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Spam Filters: How To Avoid Them When Sending Emails

Updated: Sep 16, 2019

Spam Filters:  How To Avoid Them When Sending Emails

Modern spam filter systems detect spam emails and sort them out. The recipient never gets to see them. However, many desired emails are also mistakenly classified as spam. This is annoying for you, the sender and your recipients. Find out how to manage your emails in the inboxes of your subscribers in this article.

The assessment of spam emails

Spam messages are considered to be impersonal messages, largely identical, which are sent in bulk without the prior consent of the recipient or contain content irrelevant to him.

Basically, a distinction is made between two types of spam: Criminally motivated messages and unwanted marketing e-mails. The first group includes backscatter (automatic reply emails sent by forged sender addresses) and phishing emails (fraudulent e-mails sent to capture sensitive data such as customer login, bank details, etc.).

Unsolicited marketing emails include Unsolicited Commercial Emails and Unsolicited Bulk Emails.

Whether the message is a spam e-mail is decided by the recipient as well as the spam filter. Assessing whether emails are considered spam or not is also very much dependent on the recipient's interest. Decisive is the annoying character perceived for the recipient. Exceptions are, of course, backscatter and phishing emails. These are by their very nature referred to as spam.

However, if a subscriber receives too many e-mails in a row and/or the contents are irrelevant to him, then e-mails can also be perceived as spam, where the recipient has already given their consent for such emails. Such emails are also referred to as bacn or graymails.

Bacn refers to e-mails that are generally welcome to the recipient, but not at the time he receives them. Graymails, on the other hand, are regarded as messages that are no longer relevant to the recipient despite the permission given.

This is how spam filters work

The huge amount of unwanted emails requires the use of spam filters. To make sure that your emails are not considered spam, you must have a basic understanding of how spam

filters work.

Spam filters are programs that try to evaluate unwanted e-mails among the incoming messages for their relevance and, if necessary, identify them as spam. Today's spam filters

are very complex. Messages are scored using fixed rating parameters embedded in a spam score system.

Evaluation parameters include, for example, certain words or phrases in sender address, subject line and in the e-mail itself. In addition to such text modules, spam filters work with the so-called reputation concept. Attached to certain criteria (sender, open rate, click-through rate, spam complaints, etc.) a score value is calculated by increasing the number of databases.

The specific design of this rating system is determined individually by the respective e-mail provider. This means that what is declared as spam for one provider can be classified as a "normal" message for another.

E-mails declared as spam are then either deleted or stored in a specific folder. In addition, the user has the opportunity with certain spam settings to create a rating system himself.

Get the consent of the recipient

Although this should be self-evident from a legal point of view, you should always make sure that you have obtained permission to send from the intended recipient. However, as many companies continue to believe that e-mail addresses can be purchased, one cannot say this often enough.

An effective way to guarantee a secure delivery is when your sender address is entered in the recipient's address book. Since this is hardly done, especially in the B2C area, you should ask your subscribers to enter your e-mail address in their own address book.

This request should be made as early as possible, preferably at the first regular newsletter. The reason: Since the subscriber has just decided to subscribe to your newsletter, the likelihood that he will open your first e-mails at this time is particularly high.

Avoid dubious words and phrases

Although spam filters take different criteria into account when analyzing e-mail, and evaluating phrases is just one of many evaluation criteria, you should avoid specific

words and phrases. These include phrases such as "click here", "limited offer", "access now", "must be 18" and "only available today".

The fingers should also keep you from using more than one exclamation point (!!!). In general, it is also important to be careful with strong punctuation marks such as question and exclamation points. Also avoid words or complete sentences written in uppercase.

Be transparent

If you send an e-mail with the latest online shop offers to your recipients, then you make this clear in the subject line.

It is an annoyance to subscribers when they open an e-mail under false assumptions and find something different than what's stated in the subject line. Not only is the probability relatively low that they follow one of the offered links. It can also happen that they mark your e-mail as spam. In the worst case, they opt out completely from your newsletter.

In order for the recipients to open your e-mails at all, you should of course rely on a reputable sender address. Dubious sender addresses like should be

avoided. The more spammy the sender address appears, the higher the likelihood that e-mails by this sender will be filtered out.

Suitable addresses are, for example, or

Send via secure servers

Spam filters pay close attention to the server from which the emails are sent. The easiest way to detect legitimate emails is by checking the IP address of the sending server. If this is on the list of registered and certified senders, you have overcome the first hurdle. Therefore, choose a reputable e-mail provider for your e-mail campaigns. This will usually be listed in the common whitelists. Check for possible configurations of the mail server.

Register with a whitelist

The whitelist is the alternative to a blacklist (a directory of IP addresses that are considered spam) and can be considered a kind of certification. A whitelist basically

serves to reduce the false positive risk (which is the inadvertent classification of wanted email as spam) of a spam filter system.

Any IP address and/or domain that manages to be listed there will usually be successfully delivered to the inboxes of all recipients. Well-known whitelists are The DNS Whitelist and The Spamhaus Whitelist.

If you are successfully enrolled in a whitelist, you will not have a free ticket to send emails with any content to your subscribers. If you do not follow the rules, you run the risk of being removed again.

In addition to the well-known whitelist, each recipient has the opportunity to create a personal whitelist. As an email marketer you should try to get into this whitelist. To ask you best your subscribers directly to move your email address there. This is possible with little effort.

One possibility is a pre-header request "Please add this address to your address book / contact list to receive the newsletter safely". You can also ask your recipients to look into the spam folder (also known as junk folders by some providers) and if they have an email from you, to mark them as non-spam. This setting remembers the e-mail provider in question and lets your emails through in the future.

In addition to the successful deliverability you benefit from a better presentation. This way, sent pictures are displayed immediately and do not have to be activated via "Load pictures". An e-mail provider disarms (deactivates) links when in doubt about the source address of the message. However, if this is in a (personal) whitelist, then the sent links remain unaffected.

Avoid an aggressive sending frequency

The e-mail is an ideal medium to keep in touch with your target audience. You should still avoid too high a sending frequency. Some spam filters rate an extremely high sending frequency as a potential spam sign. So it can happen that you as a legitimate sender inevitably end up in the spam folder.

Whatever your email is or is going to be about should be made clear to subscribers when they sign up. Depending on the company, this may be the latest shop offerings, a new blog article, or relevant company or industry news. Ideally, when subscribing to the newsletter, you should let them know how often you will get in touch with which content.

Clean up your subscriber list regularly

Although you may find it difficult, you should periodically check your mailing list for so-called "e-mail corpses" and file them manually. The deliverability rate and open rate are also an important indicator of whether this is an unwanted e-mail. Some non delivery and non-disclosure are normal.

But if, with a high percentage, the message is undeliverable (there is no longer an e-mail address) or is not opened, you may be misinterpreted. It can also happen that recipients who have not opened your e-mails for a long time mark their messages as spam at some point. Both should be avoided.

Be careful when delivering. During a cleanup, you should review each subscriber individually and submit it manually. Although professional e-mail providers offer the option of automated removal, you should refrain from doing so. Otherwise, you may inadvertently unsubscribe "active" subscribers as well.

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