How to bypass spam filters and get your email delivered to the inbox

This is a topic that may be of interest to many internet marketers as well as brands.
So how do you bypass spam filters and get your email delivered to the inbox?

First step: Understand how spamfilters work

One of the first realizations you'll need to get is that spam filtering these days is an entirely automatic process.

Even though sometimes it might feel like there's a person who is manually reviewing your email and deciding that it looks like spam so it should be filtered - the reality is, it doesn't really work like that.  

The amount of emails sent daily is nearly 400 Billion emails - even the smallest ISPs will still get hundreds of thousands of emails.  DAILY!   There's no way a person will sit and manually review every email.

So everything is automatic, and spam filters are just very clever, so in order to bypass them, you'll need to understand the process in which they work to detect spam.   Let's go over them by order of importance.

First criteria of detecting spam: Volume and Speed

Let's assume, for the purposes of this example, that you are a sender named someone@someplace.com.

You start sending your brand new email campaign to users of some server, let's say Hotmail.   If Hotmail doesn't "know" you yet (you are a brand new sender to them) then the system will give you a short time period of trying to "learn" your sending behaviour.

Now you might assume that's it's ok to just blast away all your emails as fast as you can, but this is exactly the type of behaviour that triggers a suspicious mark on you, as a sender.   Because you see, this is exactly what spammers do - they try to blast away their emails as fast as possible, before they get "detected" and filtered.

So the first criteria of spam filtering that you have to bypass through, in order to be considered a legitimate sender (and thus - all your emails will be delivered to the inbox), is this criteria - volume and speed.

You'll need to start slow.  Very slow, in fact.   And then gradually increase your volume and speed.   This is the kind of behaviour that is accepted and in fact it also makes sense - the growth graph of almost every business out there starts slow and then gradually increases - No business ever gets opened and immediately, within it's first hour of opening, already starts blasting tens of thousands of emails.  Think about it.

Second criteria of detecting spam: Spamtraps

Remember the "it feels like a person is manually reviewing your email.." phrase at the beginning of this article?   Well, there's no person who really sits there.   Most likely, it's either you failed in the volume and/or speed criteria (see above), or that there is an automated spamtrap address, or even a few of them, inside your lists.

Spamtraps are usually old and abandoned email addresses that haven't been used for a very long time.  VERY LONG time.   Which is exactly why they shouldn't end up in your "brand new" email list - they are dead addresses.   There's no human person who manually confirmed the inclusion of these addresses in your list.   So if you email them, it means that you are sending email to people who didn't request it, which makes you a "spammer".   

So when your email arrives at these addresses, an automated process just evaluates the person who sent this email (you) and within a very short time marks you as a "spammer" and that all your further emails should be ignored and/or filtered.   It's actually a very clever mechanism!

So in order to get your emails delivered to the inbox, you have to make sure there are no spamtraps in them - only real and valid email addresses.   Your best choice of action to evaluate this, is by sending a confirmation email first to your list to see who is interested in receiving your email, and who is not.  This is actually the suggested method by major ISPs as well.

Third criteria of detecting spam: Invalid addresses / Hard bounces

This goes back again to the common spammer behaviour.   Spammers just take an email list and starts blasting them.  We talked about this already in the first criteria (volume and speed).   In addition, most of their lists contain invalid email addresses, so they get a relatively HIGH bounce rates.

Most legitimate email senders perform list hygiene practices to remove dead addresses and or invalid or inactive users.   This goes back again to the second criteria above (spamtraps).   Because dead email addresses might turn, in time, to spamtraps, no legitimate sender will want them in his list.   So a legitimate sender might have as few as less than 0.5% of this list having invalid addresses.   This is considered a realy good value.

But, if you have 30% of your list as invalid addresses, then that's a real problem.   Not only that it might be that at least a couple of these invalid addresses are spamtraps (and thus - marking you as a spammer) but also it triggers the alarms of ISPs about you as a bad sender - which you DON'T want!

The solution to this?  Again, same solution as in the spamtraps section - send a confirmation email, first, to your list.   You might want to consider using email validation services to remove invalid addresses from your list even before you send your confirmation email.

Fourth criteria of detecting spam: Spam complaints

This just makes sense.   Maybe even more than the first 3 criterias I explained previously - if alot of users are clicking the "This is spam" button, or "complaining" about you, as a sender, then most chances are - you are a spammer.

However, you might actually be surprised to discover that this criteria is not that much important as the other 3 I mentioned earlier, you may ask.. why?

Well the first reason is, that most people who mark your email as "This is spam" don't even open your email in the first place.   They just see an unknown sender in their list, and just mark it with a checkbox and remove it.   Just the same as using the "Delete" button, but they do it with "This is spam" button.

The second reason is, and this may come as a surprise to you - is that many people will actually OPEN emails from unknown senders, mostly out of curiousity.   And when this happends, if the email actually looks legitimate and looks safe, they may either click on it, or just use the "Unsubscribe" link inside of it, instead of marking it as spam - which is exactly WHY you want to make the Unsubscribe link as easy to find as possible.

Another problem with relying on spam complaints as an indication for spam is market competition - If two companies compete against each other for clients, and both of them have the same clients, one company can give incentives to some of their clients, to mark the other company's emails as "Spam", which then makes many legitimate emails be filtered as spam without no reason.   Big problem!

So, I believe that ISPs take into consideration the spam complaints rate only if it is a VERY high rate (above 3% of overall emails sent), but they give it some percentage from the entire score, and that they have other measures which are alot more "reliable" to detecting spam, than just spam complaints (like volume and speed, spamtraps, invalid users, etc).

Fifth and final criteria of detecting spam: Content

You might think that content should be the first criteria for detecting spam, not the last.   But there's a reason why it's the final decision maker and I'll explain it.

Some of the best spammers know how spam filters work.   They know that they search for volume and speed, so they bypass them.   They know that they use spamtraps for marking the senders.   They know that they test the invalid addresses amount, and they know how relatively unimportant spam complaints are.

So what they do is they just impersonate to be a thousand different senders, using a thousand different servers, all used to send the same email.

In this case, spam filters can't realy detect the "sender", because it changes all the time.   And all the big criterias for detecting this email as spam fall in place - You can't assign volume and speed, spamtraps, and unknown users penalties to a specific sender.

But there's one thing that does remain constant, in this scenario, which is the content itself.

So, as a final line of defence, if all others fail, spam filters will look for patterns of content that repeat themselves, and mark those.

This is, of course, considered very bad behaviour, and is definitely not something that a legitimate sender will EVER do, so I don't realy think you should ever have a problem with this level.

What If I followed ALL these and still get filtered?

So you have a perfectly clean list - No spamtraps, No invalid addresses.

And you still get filtered and arrive at the spam folder, and not the inbox.

What do you do in such case?

Well, first - you can always try and contact the email provider where your recipients reside in itself and let them know of this issue.   I find that alot of ISPs are actually willing to help in such cases.

Second, you may want to check how you send your email.   Some ISPs will be more strict than others about themes like Authorization, for instance (SPF records, DKIM, DMARC), or security (using a secure channel, like STARTTLS, to send emails).

Third, if you are not sure, try to send a simple text email to one of the servers you are filetered in.   Just a regular plain email.   This SHOULD go through.    If this doesn't work, try to change the sender's name several times.   If that doesn't work, try to change your sending IP address.   And if that doesn't work, try to change your email sending infrastructure or even try sending the email from a different infrastructure.   At least ONE of these combinations SHOULD work, and it may help you in debugging the issue and/or reason for why you are filtered.

Sometimes, you get filtered because of your sender name.   This is something you don't realy have alot of control over, because some spammer can just start sending emails and impersonate to be you.   This is why authorization themes like SPF, DKIM, and DMARC, were created.

Sometimes, you get filtered because your mailing infrastructure doesn't work properly, or doesn't generate a completely valid RFC email.

Sometimes, your server IPs might belong to a neighbourhood of IPs that have been known to send spam.

And sometimes, it can actually be some problematic words inside your content that are triggering the "alarms" of spam filters.

I hope this post helped you.