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.

  • Administrative prohibition – envelope blocked – https://community.mimecast.com/docs/DOC-1369#
  • Email rejected due to security policies – https://community.mimecast.com/docs/DOC-1369#
  • Envelope blocked – User Entry – https://community.mimecast.com/docs/DOC-1369#550
  • Invalid Recipient – https://community.mimecast.com/docs/DOC-1369#
  • Message expired -> Open relay not allowed – https://community.mimecast.com/docs/DOC-1369#451
  • Rejected by header based Blocked Senders: address@example.com – https://community.mimecast.com/docs/DOC-1369#
  • Rejected by header based manually Blocked Senders: address@example.com – https://community.mimecast.com/docs/DOC-1369#
  • Remote server returned message denied by administrative policy -> Administrative prohibition – envelope blocked – https://community.mimecast.com/docs/DOC-1369#550
  • spamcop.mimecast.org Blocked – see http://www.spamcop.net/bl.shtml?10.10.10.10. – https://community.mimecast.com/docs/DOC-1369#550

If you look at the page linked to you can see that there is a huge amount of flexibility in how and who can block mail using mimecast. Mimecast itself can push filters, local administrators can filter mail for the particular domain they manage, and individual users can set up filters. And, users seem to take advantage of that.
Dealing with a mimecast block involves figuring out who is responsible for the block. Luckily, the mimecast rejection messages and documentation give clues as to whether it’s the local administrator configuring the policy or if it’s the end user. In most cases it’s not actually mimecast blocking the mail.
Mimecast provides tools and an interface to manage incoming mail, but does not actually push out rules like many of the other appliances. That’s good and that’s bad. It’s good because you don’t have a 3rd party making delivery rules for different businesses. It’s bad because once a company administrator gets to the point of blocking specific mail it’s going to be very difficult to convince them to lift that block.
Why? Remember the discussion about productive mail?
Productive Mail: Mail that furthers a business’ goals and supports their underlying business model. Mail can be both solicited and wanted by specific endusers. But, a particular company can decide to block mail simply because they don’t see the mail as beneficial to the overall business. Thus the mail is blocked for being unproductive.
We can assume that employees who have access to create mail blocks in mimecast, and other business filters, have the authority to do so. Which means when you’re looking to get unblocked through mimecast, you’re likely having to convince the very person who blocked you to unblock you.
These types of blocks are distinctly different than negotiating with a consumer ISP or even a filtering company. There is no appealing to engagement or appealing to solicited. The business doesn’t really care about either, all they care about is their employees are working while they’re at work and using corporate resources.

Back to the office!
The inbox is a moving target

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Permission and B2B spam

Two of the very first posts I wrote on the blog were about permission (part 1, part 2). Re-reading those posts is interesting. Experience has taught me that recipients are much more forgiving of implicit opt-in than that post implies.
The chance in recipient expectations doesn’t mean, however, that permission isn’t important or required. In fact, The Verge reported on a chatbot that will waste the time of spammers. Users who are fed up with spam can forward their message to Re:Scam and bots will answer the mail.
I cannot tell you how tempted I am to forward all those “Hey, just give me 10 minutes of your time…” emails I get from B2B spammers. I know, those are actually bots, but there is lovely symmetry in bots bothering one another and leaving us humans out of it.

Speaking of those annoying emails, I tweeted about one (with horrible English…) last week. I tagged the company in question and they asked for an example. After I sent it, they did nothing, and I continued to get mail. Because of course I did.
These types of messages are exactly why permission is so critical for controlling spam. Way more companies can buy my email address and add me to their spam automation software than I can opt-out of in any reasonable time frame. My inbox, particularly my business inbox, is where I do business. It’s where I talk with clients, potential clients, customers and, yes, even vendors. But every unsolicited email wastes my time.
It’s not even that the mail is simply unwanted. I get mail I don’t want regularly. Collecting white papers for my library, RSVPing to events, joining webinars all result in me getting added to companies’ mailing lists. That’s fair, I gave them an email address I’ll unsubscribe.
The B2B companies who buy my address are different. They’re spamming and they understand that. The vendors who sell the automation filters tell their customers how to avoid spam filters. Spammers are told to use different domains for the unsolicited mail and their opt-in mail to avoid blocking. The software plugs into Google and G Suite account because very few companies will block Google IPs.
I’ve had many of these companies attempt to pay me to fix their delivery problems. But, in this case there’s nothing to fix. Yes, your mail is being blocked. No, I can’t help. There is nothing I can say to a filtering company or ISP or company to make them list that block. The mail is unwanted and it’s unsolicited.
The way to get mail unblocked is to demonstrate the mail is wanted. If you can’t do that, well, the filters are working as intended.
 

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What kind of mail do filters target?

All to often we think of filters as a linear scale. There’s blocking on one end, and there’s an inbox on the other. Every email falls somewhere on that line.
Makes sense, right? Bad mail is blocked, good mail goes to the inbox. The bulk folder exists for mail that’s not bad enough to block, but isn’t good enough to go to the inbox.
Once we get to that model, we can think of filters as just different tolerances for what is bad and good. Using the same model, we can see aggressive filters block more mail and send more mail to bulk, while letting less into the inbox. There are also permissive filters that block very little mail and send most mail to the inbox.
That’s a somewhat useful model, but it doesn’t really capture the full complexity of filters. There isn’t just good mail and bad mail. Mail isn’t simply solicited or unsolicited. Filters take into account any number of factors before deciding what to do with mail.

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Feedback loops

There are a lot of different perspectives on Feedback Loops (FBLs) and “this is spam” buttons across the email industry.
Some people think FBLs are the best thing since sliced bread and can’t figure out why more ISPs don’t offer them. These people use use the data to clean addresses off their lists, lower complaints and send better mail. They use the complaints as a data source to help them send mail their recipients want. Too many recipients opted out on a particular offer? Clearly there is a problem with the offer or the segmentation or something.
Other people, though, think the existence of “this is spam” buttons and FBLs is horrible.  They call people who click “this is spam” terrorists or anti-commerce-net-nazis. They want to be able to dispute every click of the button. They think that too many ISPs offer this is spam buttons and too many ESPs and network providers pay way to much attention to complaints. The argue ISPs should remove these buttons and stop paying attention to what recipients think.
Sadly, I’m not actually making up the terminology in the last paragraph. There really are who think that the problem isn’t with the mail that they’re sending but that the recipients can actually express an opinion about it and the ISPs listen to those opinions. “Terrorists” and “Nazis” are the least of the things they have called people who complain about their mail.
One of the senior engineers at Cloudmark recently posted an article talking about FBLs and “this is spam” buttons. I think it’s a useful article to read as it explains what value FBLs play in helping spam filters become more accurate.

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