What Is HTML E-mail?

HTML email is a subset of HTML formatting and semantic tagging, which is a bad plan text in email. The text can be connected without displaying the uniform resource locator, or breaking into the uniform resource locator. Multiple events are wrapped in a window of appropriate width, instead of evenly breaking each line in 78 words. It allows self-contained images, tables, and images of figures or mathematical formulas, which are otherwise difficult to communicate (ASCIIart is generally used).

Most graphical email clients support HTML mail, and many have it by default. Many customers include one

The e-mail software complies with RFC 2822. It only needs to support plain text, not HTML formatting. Sending an HTML-formatted email can therefore cause problems if the recipient's email client does not support it. In the worst case, the recipient will see the HTML code instead of the expected message.

Some email clients that support HTML don't give it

Some senders may be overly reliant on large, colorful, or scattered fonts to make the message more difficult to read. For users who are particularly troubled by formatting, some user agents can allow readers to partially rewrite the format (for example, MozillaThunderbird allows Specify the smallest font size); however, these features are not globally available. In addition, the optical appearance difference between the sender and reader can help distinguish the author of each section and improve readability. ^[2]

Many email servers are configured to automatically generate a plain text version of the message and send it along with the HTML version to ensure that it can be read even with a plain text email client using Content-Type: multipart / alternative, As specified in RFC1521, the information itself is a multi-part / alternative type, it contains two parts, the first is the text / plain text read by the plain text client, and the second is with HTML / HTML client reads text. However, the plain text version may lose important formatting information. (For example, a mathematical equation may lose a superscript and have a whole new meaning.)

Many mailing lists intentionally block HTML e-mail, or delete the HTML part, leaving only the plain text part or rejecting the entire message.

The order of the parts is important. RFC1341 states that, in general, user agents that make up multiple-part / substitute entities should place the body parts in order of increasing priority, that is, the preferred format is the last. For multipart emails with html and plain text versions, this means listing the plain text version first and then listing the html version, otherwise the client may display the plain text version by default even if the html version is available. ^[2]

HTML email is larger than plain text. Even if no special formatting is used, the overhead of using tags in the smallest HTML document will be much higher if the formatting is overused. Multipart messages, copies of the same content in different formats, and even further increases in size. A multi-part message in plain text can be retrieved by itself, but using

HTML allows links to be displayed as arbitrary text so that the full URL is not displayed, a link may only show part of it or just a user-friendly target name. This can be used for phishing attacks, where users are fooled into thinking that the link points to a website of an authoritative source (such as a bank), accessing it, and accidentally revealing personal information (such as a bank account number) to a scammer

If the email contains a network vulnerability (embedded content from an external server, such as a picture), the server can alert the third party that the email has been opened. This is a potential privacy risk, revealing that an email address is real (so that it can be targeted in the future) and revealing when messages are read. For this reason, some email clients do not load an external image until the user requests it.

HTML content requires email programs to use an engine to analyze, render, and display documents. This could lead to more security holes, denial of service, or poor performance on older computers.

During the increase in cyber threats, the US Department of Defense converted all incoming HTML emails into text emails.

Multipart types are designed to display the same content in different ways, but this is sometimes abused; some spam emails use this format to trick spam filters into believing that the message is legitimate. They do this by including harmless content in the text portion of the message and putting spam in the HTML portion (the portion displayed to the user).

Most email spam is sent in HTML [for these reasons, spam filters sometimes give HTML emails a higher spam score. ^[2]