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.
Read articleInsights for senders.
Guides, deep dives, and updates on email deliverability, authentication, and building a bulletproof sending 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.
Read articleTroubleshooting5 min read
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.
Read articleTroubleshooting6 min read
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.
Read articleTroubleshooting5 min read
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.
Read articleTroubleshooting5 min read
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.
Read articleTroubleshooting5 min read
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.
Read articleTroubleshooting6 min read
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.
Read articleTroubleshooting6 min read
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.
Read articleTroubleshooting5 min read
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.
Read articleDeliverability7 min read
Gmail and Yahoo Sender Requirements in 2026: What Actually Gets Enforced
Since November 2025 Gmail rejects non-compliant mail at SMTP instead of spam-foldering it. The bounce codes to look for, the 0.3% line, and what to verify.
Read articleGuides6 min read
Why Does My Email Fail SPF? Reading the Record Receivers Check
SPF is a DNS list of servers allowed to send mail for your domain. It does not encrypt mail or stop spoofing alone, but receivers check it first.
Read articleProduct6 min read
The Weekly Deliverability Review: What to Check on Every Client Domain
Four signals drift without announcing it. Here is what each one means when it moves, the order to triage them in, and where a weekly pass stops being enough.
Read articleDeliverability8 min read
Why Is My Email Going to Spam? A Calm Diagnostic
Spam placement is almost always an identity or reputation problem, not a wording problem. Work the causes in the order receivers actually weigh them.
Read articleGuides8 min read
The CNIL Email Tracking Pixel Rule: What Changes on July 14, 2026
France now treats email tracking pixels like cookies. From July 14, 2026, senders need prior consent to track opens and clicks. Here is how to comply.
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