我有这个代码来发送电子邮件：
public static void sendHtmlTextWithPlainTextAlternative(final String to,
final String from, final String subject, final String plainText,
final String htmlText) throws MessagingException {
final HtmlEmail email = new HtmlEmail();
email.setHostName(SMTP);
try {
email.addTo(getStringAddresses(to));
email.setFrom(from);
email.setSubject(subject);
email.setHtmlMsg("<html><head></head><body><p>Hello World!</p></body></html>");
email.setTextMsg("Hello World!");
email.send();
} catch (final EmailException e) {
e.printStackTrace();
}
}
private static String[] getStringAddresses(final String to) {
return to.split(" |,|;|\\r?\\n|\\r");
}
但我在电子邮件客户端（Outlook 2010）中收到的只是一条纯文本消息，我可以在其中看到 html 标记和替代纯文本或空白的富文本消息（Outlook 2002）。
这是摘录
------=_Part_0_756354128.1364993577885
Content-Type: multipart/alternative; boundary="----=_Part_1_48519531.1364993577890"
------=_Part_1_48519531.1364993577890
Content-Type: text/plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
Hello World!
------=_Part_1_48519531.1364993577890
Content-Type: text/html; charset=us-ascii
Content-Transfer-Encoding: 7bit
<html><head></head><body><p>Hello World!</p></body></html>
------=_Part_1_48519531.1364993577890--
------=_Part_0_756354128.1364993577885--
根据一位 Exchange Server 管理员的说法，该消息的开头应包含类似以下内容
0 2.1.5 Recipient OK
DATA
354 Start mail input; end with <CRLF>.<CRLF>
Content-Type: multipart/mixed; boundary="----=_Part_1_933059347.1364987366297"
但它是这样的（摘录）：
250 2.1.5 Recipient OK
DATA
354 Start mail input; end with <CRLF>.<CRLF>
This is the content preamble.
------=_Part_1_933059347.1364987366297
Content-Type: multipart/alternative; boundary="----=_Part_0_1905186593.1364987366295"
电子邮件到达时主题和收件人列表都是空的。
什么可能导致这种奇怪的行为？
