Troubleshooting6 min read
550 5.7.515 in Outlook: What It Means and How to Fix It?
Outlook.com bounced the email because the From domain failed a trust check. The May 2025 rule, the 5,000-a-day line, and the DNS fix.
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Troubleshooting articles on email deliverability, authentication, and sender reputation.
Troubleshooting6 min read
Why Does My Email Fail DMARC When SPF Passes?
SPF checked the domain your platform mailed from, not the domain in your From line. That mismatch, not a broken record, is the usual reason DMARC fails.
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Why Do My Emails Go to Spam in Outlook but Not Gmail?
Gmail and Microsoft judge your mail separately. Outlook cares more about your sending IP, and complaints there stay invisible until you turn on JMRP.
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My Customers Say They Never Got My Email. Where Did It Go?
'Delivered' in your platform's log means the receiver accepted the message, not that it arrived. Four states, and one question that settles most of them.
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Why Does My Email Say "via" Someone Else's Domain?
Gmail prints that line when the domain that actually sent the message doesn't match your From address. One setting at your sending platform removes it.
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550 5.7.1 Message Rejected: Reading the Code
550 5.7.1 isn't one error. It's a family of permanent rejections, and the rest of the bounce line tells you which one you're facing.
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Why Do My Emails Go to Promotions Instead of the Inbox?
Promotions is not spam. Gmail sorted your broadcast into a tab that most people read. Three causes explain almost every case worth fixing.
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Why Are My Mailchimp Emails Going to Spam?
Mailchimp owns the sending infrastructure but cannot prove the mail is yours. Three causes explain almost every campaign that lands in spam.
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Why Are My Amazon SES Emails Going to Spam?
SES delivers whatever you hand it and takes no position on reputation. Three causes explain almost every SES message that lands in spam.
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Your DMARC Is Set to None. What Is It Actually Doing?
It collects reports and blocks nothing, so a spoofed message still reaches the inbox. Domains stall there for three reasons, each with a different way out.
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