Business Filters

Reputation is in the eye of the beholder

A few years ago reputation was generally recognised as one thing. If a sending reputation or IP reputation was good in one place it was likely good in other places. Different entities mostly reputation using the same set of signals albeit slightly tweaked to meet their own needs. More recently there is a divergence in how reputation is measured, meaning delivery can be vastly different across entities.

Who are mimecast?

Mimecast is a filter primarily used by businesses. They’re fairly widely used. In some of the data analysis I’ve done for clients, they’re a top 10 or top 20 filter.
Earlier today someone asked on Facebook if mimecast may be blocking emails based on the TLD. The short answer is it’s unlikely. I’ve not seen huge issues with them blocking based on TLD of the domain. They’re generally more selective than that.

The good news is mimecast is really pretty good about giving you explanations for why they’re blocking. They’ll even tell you if it’s mimecast related or if it’s a specific user / user-company block.
Some example rejection messages from a recent dive into some bounce logs.

Dodging filters makes for effective spamming

Spam is still 80 – 90% of global email volume, depending on which study look at. Most of that spam doesn’t make it to the inbox; ISPs reject a lot of it during the SMTP transaction and put much of rest of it in the bulk folder. But as the volumes of spam have grown, ISPs and filters are relying more and more on automation. Gone are the days when a team of people could manually review spam and tune filters. There’s just too much of it out there for it to be cost effective to manually review filters.
In some ways, though, automatic filters are easier to avoid than manual filters. Take a spam that I received at multiple addresses today. It’s an advertisement for lists to “meet my marketing needs.” I started out looking at this mail to walk readers through all of the reasons I distrusted this mail. But some testing, the same sorts of testing I do for client mails, told me that this mail was making it to the inbox at major ISPs.
What told me this mail was spam? Let’s look at the evidence.

Can I assume consumer and business filtering is the same?

Today’s question comes from Steve B.

I wondered if you know much about hosted email providers such as google apps, Microsoft and yahoo.
I have seen a rise in number of people using them to provide their corporate email service. I am using the same logic that the rules governing delivery to gmail will effect those using google hosted email for example. For Microsoft i have been using Hotmail due to the SmartScreen filters. Would you agree with that logic?
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