September/October 2018 issue of acmqueue The September/October issue of acmqueue is out now

Subscribers and ACM Professional members login here


Email and IM

  Download PDF version of this article PDF

Error 526 Ray ID: 47a87ce93b09c5f2 • 2018-11-16 08:11:37 UTC

Invalid SSL certificate








What happened?

The origin web server does not have a valid SSL certificate.

What can I do?

If you're a visitor of this website:

Please try again in a few minutes.

If you're the owner of this website:

The SSL certificate presented by the server did not pass validation. This could indicate an expired SSL certificate or a certificate that does not include the requested domain name. Please contact your hosting provider to ensure that an up-to-date and valid SSL certificate issued by a Certificate Authority is configured for this domain name on the origin server. Additional troubleshooting information here.


Originally published in Queue vol. 1, no. 8
see this item in the ACM Digital Library



Eric Allman - E-mail Authentication
Internet e-mail was conceived in a different world than we live in today. It was a small, tightly knit community, and we didn’t really have to worry too much about miscreants. Generally, if someone did something wrong, the problem could be dealt with through social means; “shunning” is very effective in small communities.

Vipul Ved Prakash, Adam O'Donnell - Fighting Spam with Reputation Systems
User-submitted spam fingerprints

John Stone, Sarah Merrion - Instant Messaging or Instant Headache?
It's a reality. You have IM (instant messaging) clients in your environment. You have already recognized that it is eating up more and more of your network bandwidth and with Microsoft building IM capability into its XP operating system and applications, you know this will only get worse. Management is also voicing concerns over the lost user productivity caused by personal conversations over this medium. You have tried blocking these conduits for conversation, but it is a constant battle.

Joe Hildebrand - Nine IM Accounts and Counting
The key word with instant messaging today is interoperability. Various standards are in contention.


(newest first)

Simon Bond | Thu, 28 May 2009 13:00:05 UTC

Ive been contemplating the issues of using whitelisting with email, and would be interested to hear your thoughts on the following.

What if.. during a "whitelist authorisation request" the remote email server responded with an instant captcha request. The sender would then be required to complete the captcha. On completion the sender would be approved and whitelisted.

Each email user would also be given the ability to chose between a captcha request (to be authorised on their whitelist) or a personal question, such as what is the opposite of happy... Or have them randomly generated.

This would dramatically reduce spam. Or... you could implement digital signatures such as those provided by verisign and if the signature passed, you would be able to bypass the above, as your details had been verified.

Just a few thoughts.... interesting article, thanks.

Leave this field empty

Post a Comment:

© 2018 ACM, Inc. All Rights Reserved.