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Best Practices

Why Is Verizon Blocking Email With "571 Email from 1.2.3.4 is currently blocked by Verizon Online's anti-spam system."?

We demystify the 571 error code sometimes returned by Verizon's mail servers.

Trends

How Web Hosting Providers Can Battle Fraudulent Sign-ups

Fraudulent sign-ups are a major problem for web hosting providers - particularly for providers offering VPS's and other flexible hosting options.

Best Practices

Why Did AOL Send Me "554 (RTR:BL) http://postmaster.info.aol.com/errors/554rtrbl.html"?

We discuss why AOL's mail servers sometimes respond with the error message "554 (RTR:BL)" and what you can do to get email flowing to AOL users.

Trends

How Botnets Send Spam (In Layman's Terms)

A guest blogger describes how and why spammers use bot nets to send spam.

Trends

What is fakemx.net and why are they temp failing me?

In this post, we discuss what fakemx.net is, and why it's generating temporary delivery failure notices in your mail server logs.

Trends

Why Is Yahoo! Temp Failing My Mail?

We explain why Yahoo! fails connections to its mail servers with error: 421 4.7.0 [TS01] Messages from 1.2.3.4 temporarily deferred due to user complaints.

Product

Policy Scripting In MailChannels

MailChannels announces Policy Scripting, a new feature to improve IP blocklist avoidance. Introducing highly flexible user behaviour monitoring & enforcement.

Trends

Most popular SMTP responses - updated for August 2012

A summary of the top-50 most popular SMTP error responses, as collected at a major web hosting provider.

Trends

How did I get 412,139 spam messages in my Gmail spam box?

How did I get 412,139 spam messages in my Gmail spam box?

Trends

The leap second that killed the Internet (well, parts of it)

A bug in various software components caused a severe global outage of various services including the popular social news site Reddit.

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