Tackling Greylisting in MailChannels Cloud

Posted: Thursday, December 10, 2015
Posted by ksimpson.

MailChannels Cloud sends enormous volumes of email through a large and complex infrastructure that spans the globe. But recently, we began encountering a serious challenge from a relatively old and yet still commonly used anti-spam technology called “greylisting”.

What is Greylisting?

According to Wikipedia, greylisting is an anti-spam technique in which the “mail transfer agent (MTA) … will ‘temporarily reject’ any email from a sender it does not recognize. If the mail is legitimate the originating server will try again after a delay, and if sufficient time has elapsed the email will be accepted.” Greylisting can be an effective defense against spam originating from simplistic botnet SMTP clients, which do not have an internal message delivery queue and cannot retry delivery if the first attempt fails (as it does when the receiving server is implementing greylisting). Legitimate email senders always … Read More »

Should I build my own mail server?

Posted: Tuesday, October 06, 2015
Posted by ksimpson.

With Edward Snowden’s revelations about government snooping into our private email, some technically-minded folks have considered setting up their own mail server in the hopes of staying clear of prying eyes. Is this a good idea? Probably not. And here’s why.

Setting up a secure email server takes a great deal of expertise and effort. You need to master a variety of protocols, from DKIM and SPF, to TLS. You also need to build a capable spam filtering system to protect yourself from email-borne offers and malware, and you need to contend with the nightmare of outbound delivery and IP blacklisting. When you’ve done all this, you also need to make sure the server is constantly kept up to date with the latest security patches, lest a global network of well funded state-level hackers gain access to your box to … Read More »

Spamhaus responds to SoftLayer’s Brazilian problem

Posted: Thursday, October 01, 2015
Posted by ksimpson.

Spamhaus, the world’s leading IP reputation advisory service, today released an analysis of an ongoing spamming issue at IBM’s SoftLayer web hosting subsidiary. According to Spamhaus, spammers have been targeting weak security measures at SoftLayer to obtain large numbers of IP addresses from which to send spam targeting Brazilian recipients. As a result of the spamming activity, Spamhaus has listed several hundred IP addresses owned by the provider under the common heading “Massive source of malware-distribution spam”.

Spammers routinely target web hosting providers like SoftLayer in an effort to obtain new resources from which to send spam campaigns. As Spamhaus and other IP reputation outfits block the offending IP addresses, spammers are hard at work exploiting any weaknesses in the provider’s security posture to obtain more. In the present situation, according to Spamhaus, the provider is not doing enough to … Read More »

STARTTLS Adoption Update

Posted: Thursday, October 01, 2015
Posted by ksimpson.

Updated October 1, 10:40am Pacific

In May 2013, Facebook published a detailed survey of TLS encryption usage by the world’s email servers. That survey indicated that about 37% of mail servers (as measured by IP address) did not at the time advertise the availability of TLS encryption for protecting the privacy of email sessions and data.

Fast forward to September, 2015 and the picture is improved, but not as much as we would have hoped. Analyzing email traffic sent to a diverse set of over 17,000 25,000 Internet email servers during a two hour twelve hour period on September 30, we found that TLS encryption is now advertised by 72% of mail servers (28% do not advertise it). This implies that the TLS encryption hold-outs have been reduced from 37% to 27% – an improvement of about a third in … Read More »

New ways to battle eavesdropping

Posted: Friday, September 11, 2015
Posted by dliao.

Unless you use end-to-end encryption such as PGP, the contents of your email message may be revealed to or even silently modified by sophisticated attackers with access to Internet backbone traffic. To prevent eavesdropping and modification, Internet engineers developed the Transport Layer Security (TLS) protocol, which email servers use to encrypt and protect email while it transits the Internet from server to server.

Edward Snowden’s revelations in 2013 about government snooping prompted large email providers such as Microsoft® and Yahoo! to implement TLS so that servers sending email to the servers can encrypt messages during transmission. After a lengthy period of implementation and testing, about 67% of mail servers in a broad survey now support TLS.

To ensure the privacy of our customers’ email messages, MailChannels Cloud now automatically encrypts connections to receiving mail servers that support the TLS … Read More »

Uber leaks trip data and personal info via a simple Google search

Posted: Wednesday, September 02, 2015
Posted by ksimpson.

Fetching this Google search URL provides a listing of random Uber trips that were somehow indexed by the search giant’s spider:

Credit for this discovery goes to Mikko Hypponen of security firm F-Secure.

Searching for stuff on gets you information like this.

— Mikko Hypponen (@mikko) September 2, 2015

Update (4:54pm PDT)

Uber appears to have fixed the problem by amending robots.txt to explicitly deny all indexing of… Read More »

Ashley Madison users being targeted by “repair services”

Posted: Wednesday, September 02, 2015
Posted by ksimpson.

Spammers thrive on two things: large lists of victims (i.e. email addresses), and data to exploit them with. The recent breach of the cheaters’ dating web site Ashley Madison provides both, and in great quantity. Spammers have wasted no time in exploiting these victims with a variety of new campaigns.

Cloudmark reported on a blackmailing scheme recently, in which spammers target Ashley Madison users with a threat to reveal their participation in the site to family members unless a bribe is paid. Not to be out-done, we searched our own logs and discovered an entirely different type of scam: a new web site,, which fraudulently promotes a removal service that can purportedly remove all traces that someone participated in Ashley Madison. The site even provides a helpful price table with a schedule of the specific services they offer:

We … Read More »

Introducing the MailChannels Cloud Console

Posted: Monday, July 27, 2015
Posted by dliao.

Next week, we will release an entirely redesigned and updated web console that we think will delight our users. As part of the redesign, the MailChannels SMTP Relay Service is being rebranded as “MailChannels Cloud” – the old name was too long, and didn’t reflect many of the powerful capabilities we’ve been building.

We’ve worked hard over the last quarter to improve the user experience (UX) of the web console, taking into account feedback from our customers.

One of the first things you will notice when you sign in to the redesigned console is a new vertical navigation system along the left side of each page. This puts relevant links directly where you need them at all times, making it easy to find your way around the console interface.

You’ll find many of the same pages you’ve become accustomed to … Read More »

How to register for feedback loops

Posted: Monday, June 08, 2015
Email marketing  design over white background, vector illustration.
Posted by ksimpson.

Email feedback loops (FBLs) allow email receivers to tell a sending network about the complaints their users are generating about email originating from the sending network. By tuning in to FBL data, sending networks can identify problematic email traffic originating from their IP address space, such as spam messages. This information can help to pinpoint and then shut down spammers.

Many large email receivers provide FBLs, which you can freely register for by clicking on the links below:

AOL Bluetie Comcast Cox Earthlink FastMail Hosted Email Mailtrust MSN/Hot NetZero/Juno Rackspace RoadRunner Synacor Terra (Brazil) United Online Verizon Yahoo Zoho

Google’s Gmail service also offers a feedback loop, which is currently in beta. To indicate your interest in the Gmail FBL, visit this signup form. Not all senders will be accepted into their FBL program.… Read More »

Introducing Notification Center

Posted: Thursday, April 30, 2015
Posted by dliao.

Notification Center pulls together all the intelligence about your email infrastructure and makes it available in one place. It tells you important information, such as who sends the most email by volume, who are the biggest spammers, and who is having deliverability issues on your network.


Access the feature

You will find the Notification Center under the Activity section of the MailChannels console. (The Top Senders reports are now located under the Activity section.) Use the top menu to access all the Notification Center information. If you click on “Notifications” from within the Notification Center, you can access the same information from the sidebar menu.



The Monitors section lets you configure settings to be alerted about specific events. Alerts can be received by email or by webhook, and you can throttle the frequency to limit how often … Read More »