Handle email deliverability

Custom sender domain

If your sender address is using a custom sender domain, first thing is to make sure it's properly verified. See https://www.prezly.com/help/verify-your-sender-address-domain

How Prezly enhances your email deliverability

Our measures that keep your emails out of Spam folders

Things that you can do 💡

While we've taken many measures to promote email deliverability. The most important of these is to build a good reputation by following certain email best practices (i.e. don’t spam your contacts!).

Preventing your emails from being marked as spam

A few things you can do to keep your email deliverability high.

Follow the rules of the game

Keep your email list clean

Keep your unsubscribed addresses in Prezly

We don’t count people who have unsubscribed as part of your total contacts

Use a clear subject line

Keep your sender name consistent

Taking these steps will improve your overall email deliverability rate and dramatically decrease the chances of your emails ending up in a spam folder 

Why are my test and internal emails ending up in spam?

What to do if you or others using your domain aren't receiving test campaigns in your email.

Your firewall settings

This is the most common reason for test emails failing.

Some work mailboxes are set up with strict spam firewalls that can block test emails if:

How to fix it

The first two causes can be fixed by asking your IT team to whitelist emails sent from Prezly. A possible workaround in the meantime is to send your test emails to an email address outside of your work domain, for example, a free Gmail account. 

Office 365 / Outlook flags test emails as spoofing attempts

An increasingly common issue with Microsoft Office 365 / Outlook accounts is that they tend to flag test emails – and any emails that use the same address for the From and To email fields – as spoofing attempts.

A bit of background:

What is spoofing?

Spoofing happens when someone fakes an email to make it look like it’s coming from a trusted sender – like your own domain or company – when it’s actually not. It’s a common tactic used in phishing scams and can confuse email platforms, especially when sending test emails or internal campaigns.

If your domain is being spoofed, it can harm your sender reputation and hurt your email deliverability, meaning your messages may end up in spam folders or get blocked altogether.

Since Prezly sends emails on your behalf (using your domain), sometimes email platforms – especially Outlook/Microsoft 365 – can misread this and flag it as suspicious. This tends to happen when you're sending an email From and To your own domain, like when testing campaigns or sending internal pitches.

How spoofing hurts deliverability

If someone is spoofing your domain, it can hurt your sender reputation – basically, your trust score with other email platforms. A bad reputation means your real emails are more likely to end up in spam folders or get blocked entirely.

Even if you’re not the one spoofing, it’s still your domain that suffers unless your email authentication is properly set up.

How Microsoft 365 handles spoofing

Microsoft 365 has built-in tools to detect spoofing. It checks each email using SPF, DKIM, and DMARC – these are technical records that help verify if an email has truly come from your domain.

When an email doesn’t pass these checks, Microsoft 365 might:

How to fix it

One easy way to fix spoofing problems (especially with Prezly emails) is to whitelist Prezly’s IP addresses in your Microsoft 365 anti-spoofing settings. This tells Outlook that emails from Prezly are safe and trusted, so they’ll always go to the main inbox, not to junk or spam.

Doing this not only helps with test emails and internal campaigns, it also protects your domain’s sender reputation in general.

Setting this up isn’t the most user-friendly process, so we’ve created the following step-by-step guide to help. If you have trouble setting this up, your company IT team will be able to help.

Step-by-step guide to whitelist Prezly IP addresses for Microsoft 365

Access your spoofed senders list at https://security.microsoft.com/tenantAllowBlockList.

Add each of Prezly's 9 IP addresses, preceded by your domain URL.

4. Ensure that spoof type is set to External and the action is set to Allow

5. Click Add to finish your setup

And you should be good to go! 🎉

For more details please refer to the resource pages of your email management provider:

Why do I get bounced contacts when I send campaigns?

A high campaign bounce rate could indicate a poorly maintained media list

When a campaign fails to reach a particular email address because of a problem on their end – for example, the email address no longer existing or the receiving mail server being down – that email address is marked as bounced.

This bounce status is immediately reflected in your CRM and campaign report, and prevents new campaigns from being sent to that email. We do this because sending campaigns to emails that cannot receive your email would affect your deliverability rating and skew your campaign results.

After a certain time, we test the bounced email addresses again to see whether they recovered.

Using bought media lists

One reason that you might experience a particularly high bounce rate on campaigns is if you are using a media list that you purchased from an online database. This is because the information on such databases is often out of date, and the high number of people attempting to reach those emails can result in inboxes becoming overloaded and email addresses being taken down.

Unless very careful, using bought media lists can also have an impact on your spam rating and may breach the GDPR. These are some of the main reasons Prezly does not sell media lists. If you're interested, you can read more about the associated risks here.

If you are certain that the emails to which you are sending your campaigns are active and should not be bouncing, please contact us via the chat bubble in the corner of Prezly or email our support team.

I sent a campaign to myself, so why can't I see it in my inbox?

Short answer: speak with your IT team

Sometimes you'll want to include yourself in a campaign test for peace of mind, only to find that the campaign you sent to yourself never arrived.

Most of the time, this is down to your company's internal server settings.

Receiving an email from your own address – or the company domain – could look fishy to the folks down in IT, so they may have set up a filter to catch out such messages. This is also one reason that an email you send to your own address from Prezly could end up in your junk folder rather than your inbox.

If you experience a problem receiving a campaign test or mailing from Prezly, please contact your company IT team to see if they are the ones blocking it; most of the time, there is nothing we can do on our side.

However, if you're concerned that a campaign you've sent has not been delivered to your contacts, one of the following links might help you:

Or contact our support team :)

Why are my test emails being flagged as suspicious?

If your test campaigns are marked as "spam", "fake" or similar in your inbox, you may need to speak with your IT team

Some companies have a strict policy on email sending sources. So, even if you send a fully authenticated test email from your Prezly account, your company system may see an internal email coming from an external source and automatically mark it as suspicious. To test whether this is what you're experiencing, try sending the same test to your personal email address.

To fix the issue, you'll need to speak with your internal IT team about your company sending policy; there's nothing we can do on our end.

In the meanwhile, rest assured that this issue will not affect your external campaigns.