If you Google a search term such as “emails not getting delivered” you will get a huge range of reasons why this can happen, but businesses need to try to minimise the chances of it happening, where they can.
For example, most people know that email companies have lists of addresses to automatically block, to try to prevent spam and other undesirable emails getting to customer Inboxes. What many people do not know is that email servers do not just rely on those lists – they use a whole range of tools to constantly filter out possible spam, including setting their own rules for what email is or is not to be stopped, and it is this range of tools that can cause problems.
It has been estimated that up to 10% of emails blocked by email servers can be genuine emails – yet they are still quarantined, put into the server ‘Junk’ folder or marked as Spam for a number of reasons.
This is one of the most common reasons for non-deliverability of emails.
Businesses need to use best practice to minimise the risk of the other party’s email servers treating their genuine emails as Junk and this includes reducing the reasons why email servers wrongly block legitimate emails.
Here are a few tips that may help: –
Do not attach dangerous file extensions to your emails
There are a number of attachments that when opened, can execute viruses or other malware and as such can be automatically blocked by some email services – even when attached to genuine emails. There are a number of such attachments but the most common are .doc and .docx, .exe, .vbs, .msi, .com and many more. Unfortunately, Office files that run what is called ‘Macros’ can also be potentially dangerous, such as .xlxm and .pptm, although this is getting less common.
So apart from being extremely careful if you receive any of the above attachments yourself, to avoid your email getting quarantined by attachment blocking, do not attach them to your emails wherever possible.
Also do bear in mind that if you have previously sent these attachments, those email servers may automatically continue to ‘distrust’ your email address until they are told otherwise by someone at their end recipients.
PDFs are a good way of emailing documents as they cannot execute malicious code and should not be blocked. Alternatively email a link to a cloud-based storage file which can be downloaded instead, such as Dropbox, Google Drive, etc.
Do not email large files
Programs like Outlook can take fairly large file attachments but some servers may operate different rules and when dealing with large files (particularly when over 150MB) then you should be using a cloud solution such as Dropbox. By emailing a link to a particular file so that the recipient can download it themselves, you can avoid any attachment size rules as well as keeping your own email storage under control.
Bounce back error messages are good!
If you get an error message giving a reason why an email has not been delivered, don’t panic – because it is there to help troubleshooting. For example if a persons email account is full, you having misspelled the address or their server has queued the email, this helps to diagnose why you have got a phone call saying “I haven’t received it”.
Unfortunately many servers do not send bounce back error messages at all these days, to try to evade spammers, so in many cases you will not get any error message even when their email service refuses or blocks your email for whatever reason.
Enable DKIM and SPF to authenticate your email
If anyone sends emails on your behalf, they should be included in what is called your SPF record, which tells the recipient email server that they are authorised on your behalf.
DKIM signs your emails with an encrypted key and the other half of that key is provided by your domain. When the keys match, there is a higher likelihood that the emails will accepted as they have been verified as authentic.
Check your email doesn’t have ‘spammy’ characteristics
Email services use many ways to decide whether or not an email is spam and therefore be blocked or discarded. One of these is to treat any email with a ‘spammy’ subject address as suspect. For example, try to make the subject line relevant and readable. Subject lines with just “Invoice” or letters and numbers will trigger suspicion straight away.
Avoid using terms such as “stuff”, “hello”, “help” and use appropriate capitalization. Also avoid formatting in an email where possible.
Beware of the recipient!
There are times when the recipient of an email has not checked their Junk folder, or have marked an email as spam (which can tell their email service to treat emails as spam from then on) – or they can just be mistaken. Sometimes they may even be avoiding telling the truth!
The bottom line is even though 99.99% of emails get through without incident, there are so many reasons why emails can get held up at the other end that you have to try to avoid these blocks if you can. With the global email system set up as it is, everyone is at the mercy of how good (or bad) your recipients email servers are set up.
The important thing is when you have an undelivered email issue, get your email server logs checked as well as asking the recipient to check their Junk mail folder. They also need to check their own email service – it may be held up there, just not getting to the person that you sent it to. If their email service has deleted it for whatever reason, that fact should be in their logs.