Resources   >   Email Deliverability & Receiveability

Solving Your Missing Email Problems

The War On Spam !   Are You a Casualty ?

What is eMail Deliverabilty All About ?
Deliverability   -   Mail You Send Out
Receiveability   -   Mail Sent To You
Don't Forget Your Website Forms
Hmmmmmmm     This is all a bit too technical
Frequently Asked Questions
    • How does spam filtering work ?
    • What is SPF (Sender Policy Framework) ?
    • Is my router blacklisted ?
    • How do I access my spam bucket ?

You simply cannot afford to live with a situation where you are sent mail that never arrives, and equally bad is mail you send out that never gets delivered. And neither you nor your correspondent - in either case - are aware of the non-delivery. It's a cost to both parties. And it happens. All the time. It's just that most of the time you are unaware. To some extent, it will be happening to you !


Some years back there was a flood of mindless destructive viruses and worms. They were pointless products of ego and filtering systems soon destroyed and defused most. But everything evolves and they were replaced with more sophisticated income earners such as malware, trackers, trojans, keyloggers and ransomware. Your ISP filtering is quite efficient in disinfecting these and moving them to junk folders. But the same principles are now being applied to the growing flood of incoming unsolicited advertising. The resultant spam filtering, especially where enthusiastically applied, can misidentify your legitimate incoming business email (known as a false-positive) and send it to the spam or junk folders. No bounce message will be generated and after a specific time (often 30 days) it will be automatically deleted. You and the sender could be (and often are) blissfully unaware.

But there is quite a bit you can do to fix this situation. Such as some once off domain wide tweaks, a change in your mail habits, and an annual check of your domain parameters.


Regarding your Domain :
  • Get a DKIM key set on your domain.
  • Make sure your domain SPF statement is correct and comprehensive
  • Check your domain reputation
  • Regularly check your router's public IP address for blacklisting
  • Use an online service to check sample emails for deliverability issues
  • Consider a mail delivery audit
Regarding User Habits :
  • Make sure that users understand that important mail should be followed up to check it was received. The old mail confirm receipts rarely work these days.
  • What NOT TO DO when creating mail :
    • Header :   Your "From" (visible) and "ReplyTo" (hidden) mail addresses must match
    • Subject :   Never leave it blank or use the "re:" prefix with nothing behind it
    • Subject :   Never type in all capitals. Keep a mix with lowercase
    • Subject :   Don't ever use the word "FREE" anywhere. Try "no charge" instead
    • To :   Use angled brackets around the mail address :   ie <> instead of just
    • Content :   Never start with "Dear .....", especially "Dear Friend"   Just don't use "Dear..."
    • Content :   Never type in all capitals. Keep a mix with lowercase
    • Content :   If you are only showing an image (ie a pic or poster) then make sure there are a few lines of text typed in as well.
The Bottom Line for Email Deliverability:
  • When someone says they didn't receive your email then follow through. If it happens once it will repeat.
  • Ask them to check their spam buckets. The cause of the mail going in there (as recorded in the header) will probably be something you can change to fix the issue.
  • If the mail is not there, then get hold of us to start an investigation from source.
  • This is more of a serious issue than lost incoming mail as you cannot then rely on every mail getting to its destination, and there's nothing else to tell you that. Don't bank on the recipients checking their spam buckets as most people don't. And most people have auto mail receipts disabled.


  • Make sure that every user knows how to access their upstream mailbox at their ISP and ensure that they do this at least once a week. They should understand the difference between the ISP mailbox and their mail client (such as Outlook).
  • The spam folders (sometimes called spam buckets or junkmail) should be checked and legitimate mail should be dragged to the inbox from where normal download will proceed.
  • Identify a staff member who can be trained to assist users with this function.
  • Consider lifting the spam score threshhold if there are many false-positives.
    This could increase spam inflow but evaluate that on results.
  • Consider white-listing correspondent domains where a fix is dependant on them and may take time.
    This could just be a temporary measure until fixed.
Best Practice :
Know how to examine the email headers of a spambucketed false-positive email to determine how the misidentification occured. All spam filtered emails that fail have the reasons appended into the mail header. Then you can figure out what corrective action to take. This helps the user, and others in the organisation, to receive mail timeously, minimises potential mail losses. Much of the time this will be caused by your correspondents mail domains being malconfigured but let them know. Apart from their appreciation that will mean their next mail to you should come straight through.

Also see the section at the bottom of this page :- How do I access my spambucket?

The Bottom Line for Email Receivability:
  • You need to check the spam bucket in your upstream mailbox at least once a week so that you don't lose incoming mail.
  • Then find out why that mail was spam filtered and make changes to stop that happening again.


You've probably put in a lot of time and cost into preparing a website that brings in the visitors. It would be most unfortunate if all that effort was wasted because a hard won enquiry was lost simply because the form completed email was spambucketed.

Forms completed on a website are usually sent via server based mail servers and are subject to many different web variables from those that your web client sent mail encounter. So it is critical that these forms are tested regularly - and not just by filling one out and seeing if you receive it. The spam scoring may be near the threshhold positive score and the content that a user completes can be enough to tip it over the edge.

Best Practice :
We recommend that these forms should be tested with an on-line scorer and are cleaned and prepared to a near perfect level.


PC Support people, to different degrees, should be able to deal with most of these issues. Your ISP and domain custodian (often the same) would assist.

You should start with a "Mail Deliverability Audit" which will measure the extent of the problem and provide a list of problems to fix. Your ISP may provide this service and if you are hosted with us we can obviously assist in this regard.



When an email for you arrives at your ISP it is first virus scanned and then spam filtered. The spam checks are made against a sophisticated rule driven system that first mkes sure the mail is not whitelisted and then compiles the score, penalty item by penalty item. Your total score is then checked against the threshhold score for the domin. If it is lower than the threshhold then the mail is accepted. If it exceeds the threshhold then the spam score summary is appended to the email header and the email is placed in the spambucket and not in your inbox. After specified amount of time 30 days?) the spam identified email will be deleted.

WHAT IS SPF ?   (Sender Policy Framework)

Sender Policy Framework is an anti-spam measure usually implemented by larger organisations. It expects you to have a statement attached to your domain's DNS record (an ISP function) which lists the different SMTP servers that your users send their mail to. This could include MWeb, Telkom, MTN, Vodacom, etc, etc. When their mail server receives a mail from you it checks that mail's headers to determine which was the first SMTP server that accepted your mail into the internet. It then looks up your domain's SPF statement to check that the SMTP server your mail went through is in the stated list. If it isn't, then an assumption is made that the sender address is forged and this is probably spam. Usually you would receive about 60% of the threshhold spam score for a SPF failure.

IS MY ROUTER BLACKLISTED ?   (How Do I Know and What To Do)

The mail header in your mail also lists yur PCs public IP address. Something like This is the unique IP broadcast by your router and would be common to all the PCs inside your network. When your router is rebooted it loses this number and a new one is allocated by your ISP as the router logs on. Many (if not most) of these routers have been reported for spam activities (perpetrated, innocently or not, by a previous user) and now it's being used by you. Every one of your emails (organisation wide) are now carrying this compromised IP address. If the recipient's systems are filtering with blacklisting checklists then you could pick up heavily weighted spam score for this.

The only known remedy is to get your public IP (just ask Google) after a known reboot and check it with a service such as MXToolbox to ensure it is clean. If it isn't, then you need to reboot for another until you do get a clean one.


Although the following help pages are for Hetzner hosted clients, the concepts are universal.

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