In this article it mentions that TrendMicro is now treating all emails from Amazon's EC2 as coming from "Dial Up Users": likely to be spam and this is creating severe deliverability issues with their emails.

We're having all kinds of issues sending email from our app servers on Rackspace cloud (which may or may not be DUL'd) and I wonder if this isn't just a losing battle and we should try to get a different host for our SMTP server.

up vote 2 down vote accepted

First, a couple of points/caveats:

  • It’s easy to see if your IP address is listed on any of the common DULs (or other RBLs—Realtime Black Lists). Google “rbl lookup”.
  • It’s possible to have an address removed from the TrendMicro MAPS DUL. I don’t know their procedures. Also, most EC2 addresses are intentionally on a more widely-used list, Spamhaus PBL, but it’s easy to remove yourself from that list.

While I do not run an e-mail server on EC2, Amazon does provide some support for doing so. You need to fill out this form:

If approved, Amazon will remove sending limits, set your host’s reverse DNS record to whatever you request, and will work “with ISPs and Internet anti-SPAM organizations (like Spamhaus) to reduce the chance of your email sent from these addresses being flagged as SPAM.” [sic]*

* Pedantic note: “SPAM” is a luncheon meat. E-mail you do not want is “spam”. So says Hormel and they own the trademark.

To whom are you sending the email? Is it to people who sign up through a site, or is it some small number of known users? How likely are the recipients to be using aggressive filtering, and how willing might they be to whitelisting the source of the email?

If you're sending email to the general public, you'll probably be better off either finding another SMTP host or researching how to get your email properly characterized by folks like Trend Micro.

It certainly seems like sending email from EC2 is now a dicey proposition.

  • It's a variety of things, our company sets up webapps for conferences, so with each conference we have to send out a variety of different emails. – Mike Buckbee May 13 '10 at 3:14

Does Rackspace have a way to assign a static IP address to a cloud instance, like EC2's Elastic IP Addresses ? If so, take a look at assigning a static address to your SMTP server. I had similar problems with emails from our EC2 instances being marked as spam, but most of the blacklisters seemed to use the blocks of IP addresses that EC2 reserves for dynamically allocated IP addresses. When I switched to an elastic IP address for our mail server, which was in a completely different block which I believe isn't blacklisted, our emails started getting through again.

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