How to solve the problem of garbled HTML emails

Solutions to garbled html emails: 1. Print the message content on the line before the mail function; 2. Save the email content as an html file and view it; 3. Set UTF-8 encoding.

The operating environment of this article: Windows 7 system, HTML5 version, Dell G3 computer.

How to solve the problem of garbled html emails? Random garbled characters appear in the mail content

Problem description:

Assemble the data (including Chinese) into html file format and send the email to the specified user.

Using the mail function in PHP

//拼装header。指定编码utf-8，解析邮件正文中的中文$headers = "From: xxx@xxx\n";
$headers .= "MIME-Version: 1.0\n";
$headers .= "Content-type: text/html; charset=utf-8\n";
$headers .= "Content-Transfer-Encoding: 8bit\n";//拼装标题  解决中文标题乱码问题$subject = xxx;
$subject = "=?UTF-8?B?".base64_encode($subject)."?=";

mail($toEmail,$subject,$message,$headers);   // 其中$message为邮件内容主题，格式形如"<p>".$title."</p>".$message.$table."";

The text part of the received email randomly appears with garbled characters, non-special characters, and random positions. The garbled characters are different when sending emails to mac and receiving emails on windows.

• windows: Random location appears? or!
• Mac: The data location is inconsistent with the incoming data. For example, it should be xxxxAxxxxBxxxxx, and the received email is xxxxBxxxxAxxxx

When the incoming data is different, sometimes garbled characters will appear, and sometimes they will not. will appear, and the comparison has nothing to do with special characters.

windows garbled characters such as:

Troubleshooting:

1. Confirm whether the assembly is incorrect

Print the message content directly in the line before the mail function in complete html format, save it as an html file and open it. No garbled characters, consistent with what is expected.

2. Confirm receipt of the email content

View the source file of the email in Outlook (you can right-click on Mac directly, Windows does not have this function, and then save it as an html file and view it ), and found that the format of the garbled characters is inconsistent with that in step 1. For example, the label appears

3. Others

In fact, up to this point, I have been wondering what exactly is done in the mail function of php. Is it right? Hidden underlying bugs in PHP, what has been changed in the transmission process. But I couldn't find the corresponding source code to view, and I lingered here for a long time.

Because it is Chinese garbled characters, I have repeatedly confirmed that UTF-8 is set. Many search results are also related to this

In addition, the confusion of the position on the mac has considered whether there is a problem with transmission truncation, right? Too long length leads to

transfer: https://www.cnblogs.com/puzbus/archive/2013/06/07/3356342.html

Summarizing two points

• If the email content is too long, it will cause parsing problems
• Solution: Content-Transfer-Encoding: base64

Review supplement:

Question 1: What is the basis for the length limit of emails, and how to deal with long emails

php mail The upper limit is indicated in the method document (I had the impression that if the length exceeds the limit, it will be truncated, so I didn’t expect it to be a length problem when the garbled characters appeared)

The basic method of PHP sets the upper limit The basis is RFC 2822 2.1.1.

At the same time, it also provides processing suggestions, which is to split the text content into multiple lines. The assembled html structure is one line, which obviously exceeds the length.

[Recommended learning: html video tutorial]

Question 2: Why can base64 solve the problem of too long email lines?

1. To understand what base64 is, refer to the base64 notes http://www.ruanyifeng.com/blog/2008/06/base64.html. Simply put, the 3 bytes in base64 represent the ASCII 4 bytes

#2. What does this have to do with line breaks? According to RFC822 regulations, every 76 characters encoded by BASE64Encoder needs to be added with a carriage return and line feed

Question 3: What do different values ​​of Content-Transfer-Encoding mean?

Reference: MIME notes and https://www.w3.org/Protocols/rfc1341/5_Content-Transfer-Encoding.html

Personally understand that methods other than base64 have no effect of inserting line breaks, so the problem cannot be solved

Supplementary 1: The text class needs Supplementary charset

Supplementary 2: "=?[Encoding]?B?".base64_encode($subject)."?="; B represents base64 Q stands for quoted-printable

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