Why is Microsoft Outlook blocking my email and how can I fix it?

Email marketer from Reddit explains that certain words, phrases, or formatting choices in your email content can trigger spam filters. Avoid using excessive exclamation points, all caps, or spammy keywords like "free," "guarantee," or "urgent."

Email marketer from StackOverflow explains that large senders need to set up feedback loops with ISPs like Microsoft. FBLs provide data about which users are marking your emails as spam, so you can remove those users from your list.

Email marketer from Mailjet shares that Implementing email authentication protocols (SPF, DKIM, DMARC) can greatly improve deliverability and reduce the likelihood of being blocked. These protocols verify that the email is actually from the sender it claims to be.

Email marketer from Neil Patel explains that a sender's email reputation is a score that Internet Service Providers (ISPs) assign to organizations that send email. It's used to determine whether or not to deliver your messages. If you have a good reputation, your emails will be delivered. If you have a bad reputation, your emails may be blocked.

Email marketer from SendGrid explains that you should gradually increase your sending volume. Sending too many emails too quickly, especially from a new IP address, can trigger spam filters and lead to blocking.

Email marketer from GlockApps explains that firewalls might block specific ports which prevents email messages being sent. You should ensure that port 25 (SMTP), port 465 (SMTPS), and port 587 (Submission) are open.

Email marketer from Litmus shares that you should test your emails across different email clients, including Outlook, to ensure they render correctly and don't trigger spam filters. Poorly formatted emails are more likely to be blocked.

Marketer from Email Geeks finds the SDNS useful to know if you're hitting their "trap network" but not worth using beyond this. Also shares that checking the domains (especially tracking domains) on the content may reveal listings related to the blocked "part of the network."

Marketer from Email Geeks shares his experience with a similar MSN blocking issue, mentioning that MSN was responsive after a ticket was opened and indicated a domain in the sender's content was flagged. He suggests checking SNDS/JRMP for IP reputation details, though the scores may not align with delivery results.

Email marketer from ZeroBounce explains that if you are sending emails from a new IP address, you need to warm it up gradually. Start by sending small volumes of emails to engaged subscribers and gradually increase the volume over time. This helps build a positive reputation with ISPs.

Email marketer from Email Marketing Forum shares that keeping your email list clean is crucial. Regularly remove inactive subscribers and those who have unsubscribed. Sending to a list full of dead addresses can hurt your sender reputation.

Marketer from Email Geeks explains that MSN doesn't DKIM sign their SNDS confirmation emails and have a broken header. If using a Google hosted domain, Google might be bouncing the confirmation emails from MSN due to a malformed `To` header.

Marketer from Email Geeks advises that when using Microsoft's ticket system, the initial response is often a canned denial. He recommends replying to these denials to get a real person to investigate and potentially share headers to identify abusive mail streams.

Email marketer from DNS Checker explains that you should check if your domain or IP address is on any email blacklists. If you are blacklisted, it can cause your emails to be blocked by various email providers, including Outlook. Delist by following the process requested by the blacklist you are on.

Expert from Spam Resource states that a high complaint rate (recipients marking your emails as spam) can severely damage your sender reputation and cause Microsoft Outlook to block your emails. Monitor your complaint rates closely and take steps to reduce them, such as improving list hygiene and sending more relevant content.

Expert from Word to the Wise shares that Microsoft heavily weighs user engagement when filtering email, so poor engagement will cause your email to go to junk or be blocked. You should focus on sending highly relevant emails to recipients that want them.

Expert from Spam Resource explains that if your IP or domain is listed on the Spamhaus Block List (SBL), Microsoft Outlook may block your emails. Check the Spamhaus website to see if you are listed and follow their delisting process if necessary.

Expert from Spam Resource shares that if you are not authenticating your email with SPF, DKIM, and DMARC, email providers such as Microsoft can flag your emails as spam or block them entirely.

Documentation from Microsoft Support explains that if a recipient has blocked a sender, emails from that sender will be blocked. The recipient needs to unblock the sender in their Outlook settings.

Documentation from Microsoft SNDS explains that a poor IP address reputation can cause emails to be blocked. Monitor your IP reputation using SNDS (Smart Network Data Services) and ensure your sending practices are compliant with Microsoft's guidelines.

Documentation from Microsoft Support shares that to fix the error message when a message that you sent is bounced back to you. The most common reason for delivery failure is that the recipient's email address was mistyped.

Documentation from Microsoft Support shares how to ensure your email always goes to a recipient's inbox, is to get added to the Safe Senders list. Addresses and domain names in the Safe Senders List are never treated as junk email.