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<SureMailMsg type=“post_not” toAddrHash= “ 1251de1ab4532dd06851ac3ed237f809dcaa0126 ” ttl = “ 43200s ” bodyHash = “ 56893db1ea38600dbaeef123765098ad96ef9ddd ” ssId = “ 89d03cca4dba4791abed498d876ca0023abcefd1 ”
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<SureMailMsg type=“post_not” toAddrHash= “ 1251de1ab4532dd06851ac3ed237f809dcaa0126 ” ttl = “ 43200s” bodyHash =“ 56893db1ea38600dbaeef123765098ad96ef9ddd ” ssId = “ 89d03cca4dba4791abed498d876ca0023abcefd1 ” auth = “ ab11211189defa3d45c09268daaae9bc32a1223a ” /> notification 4 + 20 x 3 = 64 bytes SureMail: Notification Overlay for Email Reliability Sharad Agarwal, Dilip A. Joseph, Venkat Padmanabhan http://netprofiler Email Loss & Delay • Why ? • Aggressive spam filters • Upgrades/downtime/failure • 90% email to MSFT tossed ! • Often silent(no bouncebacks) • Delay can be as bad as loss SureMail Architecture • Client-based approach • No server mods., no PKI • Separate notification overlay • Sender: post notification • Recipient: “You’ve lost mail” Notification Format • Receiver hash H(R) • Time to live T • Email body hash H(Mnew) • Shared secret H(Mold) • Authenticator MAC([T,H(Mnew)], H’(Mold)) • Hard for spammer to spoof Experiment • 36 sending email accounts • 42 receiving email accounts • MSFT, EDU, Hotmail, Yahoo, …, US, UK, AU, NZ, CA … • Enron corpus (1266 bodies) • Attachments (DOC, JPG,…) Salient Features • Minimal disruption • Minimal demands on user • Preserves asynchronous comm., privacy, repudiability • Maintains spam, virus defense • Low overhead Results • 83 days • 158,379 emails sent • 3,183 emails lost • Loss rate 1.82% to 3.36% • Silent loss 0.71% to 0.91% • Delay: mean 276 seconds max 36.6 hours Status • Prototype implementation • Run SureMail experiment • 29 days, 19435 emails sent • All 653 lost emails caught! • HotNets 2005 paper • Patent application pending Key Mechanisms • Email-based handshake • Prevents impersonation • Reply-based shared secret • Blocks notification spam • Automatic reply detection • Based on text similarity Received: from iktulaut.web.ca (localhost [127.0.0.1]) by list.web.net (Postfix) with ESMTP id C24785A92; Wed, 29 Jun 2005 15:24:14 -0400 (EDT) Received: from post.web.ca (post.web.ca [192.139.37.29]) by list.web.net (Postfix) with ESMTP id 835755968; Wed, 29 Jun 2005 10:32:23 -0400 (EDT)