Microsoft consumer mailboxes (like Hotmail, Outlook, Live, and MSN) have strict spam filters, making it difficult for senders (even legitimate ones) to have their emails always land in the desired recipients’ mailboxes. Microsoft is harsh towards illegitimate senders and, thus, is the quickest to block messages/ senders or mark them as spam.

This doesn’t sit well, especially with email marketing experts as Outlook.com is the third-most-popular email service provider and is used by over 400 million users. This means there’s always a high possibility of marketing emails landing in junk folders. So, let’s explore if there’s anything that you, as senders, can do at your end to avoid such situations.

Key Takeaways

SPF, DKIM, and DMARC are essential protocols for establishing the legitimacy of your emails and enhancing deliverability.
Gradually warming up new email accounts can build your sender reputation and increase successful deliveries.
Signing up for Smart Network Data Service (SNDS) helps monitor your email sending reputation and address deliverability issues.
Regularly clean up your mailing list to avoid being flagged for namespace mining, which can lead to blocks from Microsoft.
Focusing on engagement and reducing emails to inactive subscribers can improve your overall sender reputation.

Microsoft OLC’s Spam Filters Aren’t Enough

Multiple complaints are scattered online about how Outlook’s spam filters have gone unreliable and unreasonable lately. Believe it or not, Outlook users have to check their junk folders multiple times a day because this is where they expect genuine conversations to land.

It’s identifying even allowlisted senders and mail servers as spam. What’s worse is that resolution of such issues takes much longer than other mailbox providers.

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How to Ensure Emails Land in Microsoft Consumers’ Inboxes?

550 5.7.1 Unfortunately, messages from [x.x.x.x] weren’t sent. Please contact your Internet service provider since part of their network is on our block list (S3150). You can also refer your provider to http://mail.live.com/mail/troubleshooting.aspx#errors. [#.eop-nam02.prod.protection.outlook.com]

If you get the above-mentioned bounce message now more than ever, then you need to renew your mailing list, get unblocked as a sender, and follow these five tips.

1. Deploy SPF, DKIM, and DMARC

SPF (Sender Policy Framework) allows domain owners to specify which IP address or mail servers are authorized to send emails on their behalf. Emails sent by any other senders are marked as spam, or they bounce back.

DKIM (DomainKeys Identified Mail) uses a pair of cryptographically-secured keys that help verify the sender’s authenticity by involving DKIM signatures on outbound emails.

DMARC tells recipients’ servers what to do with emails that fail SPF and/or DKIM checks. You can set a suitable DMARC policy to instruct them to take no action against such messages, mark them as spam, or reject their entry.

Click here to read: DMARC or email marketers.

Combining these three protocols establishes your domain as legitimate and trustworthy while keeping hackers at bay.

2. Warm-up New Email Accounts

Email warming scales your outreach by gradually instilling trust in recipient mailboxes. This builds your reputation as a legitimate sender and helps pass Microsoft OLC spam filters. You can follow this standard ramp-up routine for new email accounts-

Days	Number of maximum emails to send per day	The gap between two consecutive emails
1-3	15	450 seconds
4-7	25	400 seconds
8-10	40	250-300 seconds
11-14	70	200 seconds
15-20	150	100 seconds
21-30	200-250	>67 seconds

Go slow; it will take around 3 to 4 weeks for you to reach the number of emails you actually want to send per day.

SNDS stands for Smart Network Data Service, a reputation portal introduced by Microsoft that enables you to comprehend problems pertaining to the deliverability of your domain. Once you have signed up, request access, and check data about all your sending IP addresses. It lets you know if your emails are being marked as spam and whether your reputation is red, yellow, or green.

It’s a matter of concern if your sending IPs’ reputation is consistently being marked as red. This indicates that most people are categorizing your messages as spam-y or due to Outlook’s Spam Fighters program., popularly known as Sender Reputation Data (SRD).

Microsoft builds SRD by asking some of your subscribers if they recognize your messages as spam. If they tap on the ‘yes’ option, your deliverability gets hampered. To save your email-sending domain or IPs from this-

Renew and revise your mailing lists
Don’t buy lists from just anybody selling them off
Ensure creating valuable messages and newsletters
Refrain from putting up questionable content
Cut down your mailing list to only engaged subscribers

4. Avoid Being Mistakenly Considered a Namespace Mining Practitioner

“More information needed

177.43.254.226

There are indications that the above IP(s) are engaged in namespace mining. Outlook.com is blocking all emails sent from this IP.”

The above reply indicates that your IP/IPs are observed engaging in namespace mining. Namespace mining is the user behavior of verifying email addresses without actually sending messages to them. It’s commonly practiced by threat actors, and that’s why Microsoft condemns it outrightly.

You get tagged for namespace mining even when you don’t engage in such practice; this happens when your mailing list is old and unrevised. You are advised to go through your domain’s sending log to pull out subscribers corresponding to nonexistent @hotmail.com, @live.com, @msn.com, and @outlook.com.

5. Pull Back and Focus on Engagement

If your emails are consistently being placed in the junk folder of Microsoft OLC recipients, it’s time you take a drastic shift in your email-sending approach. Temporarily stop sending emails to subscribers that haven’t opened your messages at all in the last X days. Now, X varies from industry to industry and can be anywhere between 15 to 180 days; if you aren’t sure, start by considering X as 60 days.

If you notice any depreciation in the spam placement in the next 4-5 weeks, continue this pattern; otherwise, you can restart sending them messages.

Conclusion

We at PowerDMARC can help you take the first step by supporting you in getting started with email authentication protocols with our DMARC analyzer. We have aided thousands of customers and hundreds of organizations in building trust, protecting their domains against email fraud, and improving email deliverability. You can contact us today, and one of our experts will get back to you with the support and guidance your brand requires, or take a free 15-day trial of our platform!

About
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Yunes Tarada

Domain & Email Security Expert at PowerDMARC

Yunes is an Operations Team Lead at PowerDMARC with expert knowledge in email authentication and security. Yunes is a Microsoft-certified Azure Administrator Associate with certifications in CompTIA A+ and many more.

Microsoft OLC Email Deliverability Guide

Microsoft OLC’s Spam Filters Aren’t Enough

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