Starter
For your first email program.
$16USD / month
$192 billed yearly.
20,000 emails / month
Choose Starter- 5 brands · 3 seats
- 5 custom sending domains
- 500 email verifications/month
- $1.50 / 1,000 extra emails
Start with what happened to the message
Microsoft can reject mail during delivery, accept it into Junk, or show a warning when someone opens a link. Those results do not establish the same problem.
- Rejected: retain the complete SMTP error, sending IP, sender, recipient, time and message ID. A permanent
5xxresponse is not permission to keep resubmitting that message. - Accepted into Junk: have the recipient’s Microsoft 365 administrator inspect the message in Defender. Compare the original and latest verdicts, delivery locations, detection technology, policy overrides, timeline and URL results.
- Link warning: investigate the exact URL and redirect destinations. A URL reputation detection can occur even when the email passes SPF, DKIM and DMARC.
What reputation checks can tell you
A public blocklist result does not reveal all of Microsoft’s filtering. Outlook.com Postmaster links to SNDS, which reports data for sending IPs you control, and JMRP, which supplies complaint feedback. Neither is a universal domain-clearance certificate.
If you use a shared sending service, the provider owns those IPs. Ask the provider to investigate its IP data and include an affected message ID. Clean authentication or a clean public blocklist result alone does not establish healthy Microsoft reputation.
For accepted business mail, compare the message’s bulk complaint level with the recipient’s effective anti-spam policy. Bulk handling, ordinary spam classification and phishing detections are different findings. Do not infer one from the folder name alone.
Use the support route that matches the finding
For Microsoft 365 rejections that identify an IP block, follow Microsoft’s blocked-IP instructions. The error determines whether that portal applies. It does not fix every accepted email that reaches Junk.
For consumer Outlook.com, Hotmail or Live delivery problems, start with Outlook.com sender support. For a legitimate message or URL falsely flagged in a Microsoft 365 tenant, the recipient’s administrator can submit the affected item to Microsoft for analysis.
Keep the full headers and the original and latest detection details. A review marked “No threats found” is useful evidence, but does not guarantee that the next email will reach Inbox or that another tenant has recovered. Do not use a test allow-list as proof of a sender fix.
Meet the sending requirements first
Authenticate the provider that actually sends your email. Use an accurate sender identity, a working reply address, permission-based audiences and an easy unsubscribe. Stop sending to hard-bounced or complaining recipients and investigate repeated failures.
Nitrosend’s Microsoft delivery guide covers authentication, unsubscribe behaviour, BYO responsibilities and the evidence to collect. Our acceptable-use terms prohibit spam, purchased lists, phishing and impersonation.
FAQ
Can I check whether Microsoft blocks my domain?
There is no public lookup that proves a domain is clear of all Microsoft filtering. Inspect an affected message or rejection. SNDS provides data for IPs you control; shared sending IPs are the sending provider’s responsibility.
Why does authenticated email still reach Junk?
Authentication verifies the sender. Microsoft also considers reputation, content, links, complaints and recipient policies. Acceptance by the receiving server does not guarantee Inbox placement.
How do I request Microsoft delisting?
Use the route that matches the actual rejection. The Microsoft 365 IP-delisting portal applies to specified IP-block errors. Consumer Outlook.com issues use Outlook.com sender support. For accepted mail in Junk or a false link warning, submit the affected message or URL for review instead.