Troubleshooting rejected Emails because of Spam Filters

Owned by Gord More (Unlicensed)
Last updated: Oct 22, 2018
4 min read
To help ensure reliable email delivery of invoices and forms to your customers, IDS uses Sendgrid for mail delivery which has the highest delivery success rate in the industry.

Apart from Sendgrid, there are several factors that can affect email delivery of invoices and reports to your customers:

1) Incorrect or inadequate Domain DNS Records for your company's DNS Domain.
2) Your Domain could be on one or more Blacklists.
3) Your customers mail server or client may be blocking the incoming mail.

For You the Courier/Logistics/Delivery Company


We'll look at each of these in turn.

1) Incorrect or inadequate Domain DNS Records for your company's DNS Domain.

A good place to check these settings is at


Enter your domain (we'll use idsapp.com as an example) and click "MX Lookup."

Now below Pref Hostname IP TTL columns, your domain's "MX hostname" will be listed

In this case they are


There may be one or more MX mail servers specified that handle the delivery of email for your domain. In this example there are two. So for idsapp.com, both MX servers can deliver email for idsapp.com. If one is not available, the second one is tried, and then third, forth, etc if they are defined.

Now directly below the search box you just typed idsapp.com into, there will be a line with a green button that says

mx:idsapp.com "Find Problems"

Now click the green "Find Problems" button to make sure there are no problems listed here for your domain.

If there is a no Reverse DNS entry listed here, make sure that you MX servers have reverse DNS entries setup.

For example, if your email domain is examplecourier.com and the MX for this is mail.mastercourier.com, there should be a reverse DNS record setup for mail.mastercourier.com or recipient mail servers may reject email. For each MX server listed, make sure a reverse is defined. The listed MX server names will appear in blue and you can click them.

Here you will often get an error saying "No DMARC Record found." That's okay for now.

The error you don't want to see is "No SPF Record found." If you do, please create an SPF DNS Record for your Domain.

A page to help with this is


When you are done yor SPF Record should look like this

examplecourier.com "v=spf1 mx a ptr ~all" 3600

This entry needs to be added to your DNS Records that can typically be setup where you register your name, such as Godaddy, Google, Dreamhost, etc. Setting up DNS Records is often under an Advanced configuration Menu and you may need to get your Registrar to help with this.

If possible, setup your mail server to handle DKIM and DMARC too, but in general, SPF will be enough. More stringent receiving mail servers may require DKIM/DMARC in the future, but to date, setting up SPF DNS Records is enough to satisfy almost all mail servers on the Internet.

2) Your Domain could be on one or more Blacklists.

The MXToolBox "Find Problems" page will also list any other problems related to your domain that may affect mail delivery.

If your domain is listed on any Blacklists, you should fix the underlying reason that your domain is on the Blacklist, then login to the Blacklist's Web Site and request that your Domain be delisted and removed from the Blacklist.

There is lots of information on the Internet to help with this. For example


It will be a good idea to follow on-line help if your domain is on any Blacklists.

For Your Customer receiving the Emails. 


 Your customers mail server or client may be blocking the incoming mail.

Apart from being on a Blacklist, recipient mail servers may reject incoming email for other reasons and other security checks.

Examples of tough delivery mail servers are hotmail.com, outlook.com, and gmail.com. These are some of the biggest mail services on the Internet and they run extensive tests on incoming email to try to weed out spam.

Unfortunately we don't have much control over this. If there are delivery problems that are specific to these servers, your customers will have to contact the providers support or possible start using a different email service.

Your customer's recipient Email Account Mailbox may have SPAM or Additional Filters setup that is preventing the account from receiving the email reports.

The customer can't change these settings in their email client but can change them in the Webmail login page of their service provider. For example, at gmail.com , or at outlook.com .

Here they can adjust spam filtering levels and whitelist domains that they are receiving email from.

To test if this is the problem, try having them turn off spam filtering altogether and see if you get the reports delivered. Then tune it accordingly.

Also, it would be a good idea to have them whitelist your domain. If your Courier domain is examplecourier.com, have the customer whitelist anything being received from your domain.

Typically this will be a wildcard entry to whitelist your domain something like this

Also, have your customer whitelist everything from: internetdispatcher.org and mail.internetdispatcher.org

Lastly affecting mail delivery is sometimes customers setup filers to help sort their incoming mail into folders. These filters can be setup on their mail client or in their on-line Webmail account. Try having them turn of these filters if you have tried all the above and there continues to be delivery problems.

Last but not least is to try delivery to a different Email Account that your customer may have. If it works to a different account, you know there is still a problem delivering to the account being tested above, for one of the reasons listed.