How Can I Troubleshoot Email Delivery Problems to My Recipients?

Why aren't my recipients receiving their emails? Why are my credential emails being filtered as Spam?

What's Happening?

Recently there has been a significant increase in email client security, particularly for email addresses belonging to business domains. This is impacting delivery rates across a large number of industries and service platforms, including Accredible. Here is what you can do to improve delivery rates to your recipients and prevent your credential emails from being filtered as spam.

SMTP Setting Overrides

To increase the email delivery rate of emails sent from Accredible, we recommend implementing SMTP Setting Overrides to send email from us via an email inbox that you control. This also gives you the bonus of having the emails come from your domain address rather than Accredible's -  this is good for branding and will help avoid recipients' spam filters.

For information on how to implement SMTP Overrides, here is our article here: SMTP Setting Overrides

IMPORTANT NOTE: If you update the login credentials for your email inbox you will need to update these in your SMTP Overrides setting within Accredible also. Failure to do so could result in your emails failing to send.

Remove PDF Attachments

Currently, a lot of email client security will identify attachments on emails from unknown senders as suspicious, as this is often a common tactic malicious individuals will use to install malware on devices. Including PDF attachments on credential delivery emails is a non-essential part of Accredible's service, as the unique credential link will give your recipient access to their certificate where they can download the PDF themselves. 

If you are have having recurring problems with credential emails being sent to your recipient's spam and have the 'Include PDF attachment' setting switched on, we highly recommend turning this setting off to avoid this issue.

Include PDF Attachment Setting

Retrieve Credential Tool

As a workaround, you can direct your recipients to Accredible's Credential Retrieve Tool, where they can enter their email address and have their credentials fetched for them. We have found that the Retrieve Tool often bypasses the same delivery problems as normal credential emails, and this will give your recipient access to the credential immediately. It's also useful to make them aware of this tool. If they ever lose their credential URLs again in the future, they will always access them from the Retrieve Tool.


If your recipients belong to the same company, you can advise the company's IT team to whitelist our email sender data using the following information.

Default email sender:

IPs that email may be delivered from: and

SPF record: 


We use SendGrid for email delivery. By default, SendGrid sets the return path on any email that's delivered to your recipients to match our domain. This means that DKIM and SPF setup shouldn't be necessary, and most mail clients will be transparent about the sender and include something like 'via Accredible' in the From field.

Sender Authentication 

If you decide to use your own email, under our Sender Details, we recommend setting up Sender Authentication. This authorizes Accredible to send on behalf of your email domain and improves delivery rates. You can read more about this process here.

Note:  To begin this setup process, please reach out to

Bounced Emails 

For more information regarding bounced emails, check out our article here: Why Did the Email to my Recipient Bounce?

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