“5.x.0 Message Bounced by Administrator” – What Does it Mean?
The “5.x.0 – message bounced by administrator” falls into the “what now?” category, mainly because it’s so vague.…
Email Infrastructure ⌄ Practical strategies to improve email deliverability and performance.
Practical guidance on setup, configuration, and compliance across SMTP, DNS, authentication, IP reputation, and the systems that power email delivery.
Latest articles
Amazon SES SPF Record: Best Practices for Better Inbox Placement
You’d think email authentication would be simple: set up an Amazon SES SPF record, publish a few records,…
SPF PTR: All You Need to Know
Ever wondered how emails stay safe from scammers and hackers? That’s where SPF PTR comes in. SPF PTR…
550 5.7.0 Message Size Violation? Here’s How to Solve It
You draft an email, attach the files, press send, and back it comes with a 550 5.7.0 message…
What Does Queued Mean In Gmail? (And How to Fix It)
If you’re an active Gmail user, one of the most annoying things that can happen is a “queued”…
Dedicated Email Server: Control & the Cost of Going Solo
At some point, every serious sender gets that itch: why not just handle it all myself? The idea…
Shared Mailbox vs Distribution List: What Works Best
You’ve probably seen this before. A client sends one simple question, and somehow, five people reply. Or worse,…
HubSpot SPF Record Setup Errors That Break Inboxing
If emails sent through HubSpot are landing in spam or not being delivered at all, the SPF record…
What To Do When Reverse DNS Does Not Match SMTP Banner?
Checking your mail server’s health only to find a “reverse DNS does not match smtp banner” error is…
Which SMTP Port Should You Use for Your Mail Server?
Configuring SMTP to send email seems straightforward right until you need to fill in the port number field.…