Editing Email (section)

===Tracking of sent mail===
The original SMTP mail service provides limited mechanisms for tracking a transmitted message, and none for verifying that it has been delivered or read. It requires that each mail server must either deliver it onward or return a failure notice (bounce message), but both software bugs and system failures can cause messages to be lost. To remedy this, the [[Internet Engineering Task Force|IETF]] introduced [[Delivery Status Notification]]s (delivery receipts) and [[Return receipt#Email|Message Disposition Notifications]] (return receipts); however, these are not universally deployed in production.{{Refn|group=nb|A complete Message Tracking mechanism was also defined, but it never gained traction; see RFCs 3885<ref>RFC 3885, ''SMTP Service Extension for Message Tracking''</ref> through 3888.<ref>RFC 3888, ''Message Tracking Model and Requirements''</ref>}}

Many ISPs now deliberately disable non-delivery reports (NDRs) and delivery receipts due to the activities of spammers:
* Delivery Reports can be used to verify whether an address exists and if so, this indicates to a spammer that it is available to be spammed.
* If the spammer uses a forged sender email address ([[email spoofing]]), then the innocent email address that was used can be flooded with NDRs from the many invalid email addresses the spammer may have attempted to mail. These NDRs then constitute spam ([[backscatter (email)|backscatter]]) from the ISP to the innocent user.

In the absence of standard methods, a range of system based around the use of [[web bug]]s have been developed. However, these are often seen as underhand or raising privacy concerns,<ref>{{cite news|url=https://query.nytimes.com/gst/fullpage.html?res=940CE0D9143AF931A15752C1A9669C8B63|title=Software That Tracks E-Mail Is Raising Privacy Concerns|author=Amy Harmon|newspaper=The New York Times|date=2000-11-22|access-date=2012-01-13}}</ref><ref>{{cite web |url=https://email.about.com/od/emailbehindthescenes/a/html_return_rcp.htm |title=About.com |publisher=Email.about.com |date=2013-12-19 |access-date=2014-01-09 |url-status=live |archive-url=https://web.archive.org/web/20160827203219/https://email.about.com/od/emailbehindthescenes/a/html_return_rcp.htm |archive-date=2016-08-27 }}</ref> and only work with email clients that support rendering of HTML. Many mail clients now default to not showing "web content".<ref>[https://www.slipstick.com/outlook/email/microsoft-outlook-web-bugs-blocked-html-images "Outlook: Web Bugs & Blocked HTML Images"] {{webarchive|url=https://web.archive.org/web/20150218074718/https://www.slipstick.com/outlook/email/microsoft-outlook-web-bugs-blocked-html-images/ |date=2015-02-18 }}, slipstick.com</ref> [[Webmail]] providers can also disrupt web bugs by pre-caching images.<ref>[https://arstechnica.com/information-technology/2013/12/gmail-blows-up-e-mail-marketing-by-caching-all-images-on-google-servers/ "Gmail blows up e-mail marketing..."] {{webarchive|url=https://web.archive.org/web/20170607090403/https://arstechnica.com/information-technology/2013/12/gmail-blows-up-e-mail-marketing-by-caching-all-images-on-google-servers/ |date=2017-06-07 }}, Ron Amadeo, Dec 13 2013, Ars Technica</ref>