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.

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AHBL Wildcards the Internet

AHBL (Abusive Host Blocking List) is a DNSBL (Domain Name Service Blacklist) that has been available since 2003 and is used by administrators to crowd-source spam sources, open proxies, and open relays.  By collecting the data into a single list, an email system can check this blacklist to determine if a message should be accepted or rejected. AHBL is managed by The Summit Open Source Development Group and they have decided after 11 years they no longer wish to maintain the blacklist.
A DNSBL works like this, a mail server checks the sender’s IP address of every inbound email against a blacklist and the blacklist responses with either, yes that IP address is on the blacklist or no I did not find that IP address on the list.  If an IP address is found on the list, the email administrator, based on the policies setup on their server, can take a number of actions such as rejecting the message, quarantining the message, or increasing the spam score of the email.
The administrators of AHBL have chosen to list the world as their shutdown strategy. The DNSBL now answers ‘yes’ to every query. The theory behind this strategy is that users of the list will discover that their mail is all being blocked and stop querying the list causing this. In principle, this should work. But in practice it really does not because many people querying lists are not doing it as part of a pass/fail delivery system. Many lists are queried as part of a scoring system.
Maintaining a DNSBL is a lot of work and after years of providing a valuable service, you are thanked with the difficulties with decommissioning the list.  Popular DNSBLs like the AHBL list are used by thousands of administrators and it is a tough task to get them to all stop using the list.  RFC6471 has a number of recommendations such as increasing the delay in how long it takes to respond to a query but this does not stop people from using the list.  You could change the page responding to the site to advise people the list is no longer valid, but unlike when you surf the web and come across a 404 page, a computer does not mind checking the same 404 page over and over.
Many mailservers, particularly those only serving a small number of users, are running spam filters in fire-and-forget mode, unmaintained, unmonitored, and seldom upgraded until the hardware they are running on dies and is replaced. Unless they do proper liveness detection on the blacklists they are using (and they basically never do) they will keep querying a list forever, unless it breaks something so spectacularly that the admin notices it.
So spread the word,

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Parasites hurt email marketing

As a small business owner I am a ripe target for many companies. They buy my address from some lead generation firm, or they scrape it off LinkedIn, and they send me a message that pretends to be personalized but isn’t really.
“I looked at your website… we have a list of email addresses to sell you.”
“We offer cold calling services… can I set up a call with you?”
“I have scheduled a meeting tomorrow so I can tell you about our product that will solve all your technical issues and is also a floor wax.”
None of these emails are anything more than spam. They’re fake personalized. There’s no permission. On a good day they’ll have an opt out link. On a normal day they might include an actual name.
These are messages coming to an email address I’ve spent years trying to protect from getting onto mailing lists. I don’t do fishbowls, I’m careful about who I give my card to, I never use it to sign up for anything. And, still, that has all been for naught.
I don’t really blame the senders, I mean I do, they’re the ones that bought my address and then invested in business automation software that sends me regular emails trying to get me to give them a phone number. Or a contact for “the right person at your business to talk to about this great offer that will change your business.”
The real blame lies with the people who pretend that B2B spam is somehow not spam. Who have pivoted their businesses from selling consumer lists to business lists because permission doesn’t matter when it comes to businesses. The real blame lies with companies who sell “marketing automation software” that plugs into their Google Apps account and hijacks their reputation to get to the inbox. The real blame lies with list cleansing companies who sell list buyers a cleansing service that only hides the evidence of spamming.
There are so many parasites in the email space. They take time, energy and resources from large and small businesses, offering them services that seem good, but really are worthless.
The biologically interesting thing about parasites, though, is that they do better if they don’t overwhelm the host system. They have to stay small. They have to stay hidden. They have to not cause too much harm, otherwise the host system will fight back.
Email fights back too. Parasites will find it harder and harder to get mail delivered in any volume as the host system adapts to them. Already if I look in my junk folder, my filters are correctly flagging these messages as spam. And my filters see a very small portion of mail. Filtering companies and the business email hosting systems have a much broader view and much better defenses.
These emails annoy me, but I know that they are a short term problem.  As more and more businesses move to hosted services, like Google Apps and Office365 the permission rules are going to apply to business addresses as well as consumer addresses. The parasites selling products and services to small business owners can’t overwhelm email. The defenses will step in first.
 

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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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