晚了几年，但这就是它对我的工作方式，也许这会对遇到这个问题的其他人有所帮助。
我从来没有尝试过 TZOFFSETFROM ......所以不确定那是什么，或者即使它应该工作。但是，如果你把 Timezone 放在 DTSTART 和 DTEND 中，它会自动调整。您只需要使用 UTC 的日期，就像您的最后修改日期一样。我这样做（$start并且$end是 PHP DateTime 对象）：
"DTSTART:".$start->setTimezone(new DateTimeZone('UTC'))->format('Ymd\THis\Z').$eol.
"DTEND:".$end->setTimezone(new DateTimeZone('UTC'))->format('Ymd\THis\Z')
因此，基本上，所做的只是将日期放入 UTC 时区，然后在最后用 Z 格式化日期/时间，以便将其传达给客户端。
一个完整的工作示例（如果它对任何人都有帮助）是：
<?php
date_default_timezone_set('America/New_York');
//CONFIGURE HERE
$fromName = "John Doe";
$fromEmail = "john.doe@example.com";
$toName = "Your Name";
$toEmail = 'yourname@example.com';
$start = new DateTime('2017-08-15 15:00');
$end = new DateTime('2017-08-15 16:00');
$summary = "Hello World Event";
//END CONFIGURATION
$uid = "0123456789";
$headers = array();
$boundary = "_CAL_" . uniqid("B",true) . "_B_";
$headers[] = "MIME-Version: 1.0";
$headers[] = "Content-Type: multipart/alternative; boundary=\"".$boundary."\"";
$headers[] = "To: \"{$toName}\" <{$toEmail}>";
$headers[] = "From: \"{$fromName}\" <{$fromEmail}>";
$calendarLines = array(
"BEGIN:VCALENDAR",
"METHOD:REQUEST",
"PRODID:-//PHP//MeetingRequest//EN",
"VERSION:2.0",
"BEGIN:VEVENT",
"ORGANIZER;CN={$fromName}:MAILTO:{$fromEmail}",
"ATTENDEE;ROLE=REQ-PARTICIPANT;PARTSTAT=NEEDS-ACTION;RSVP=TRUE;CN={$toName}:MAILTO:{$toEmail}",
"DESCRIPTION:{$summary}",
"SUMMARY:{$summary}",
"DTSTART:".$start->setTimezone(new DateTimeZone('UTC'))->format('Ymd\THis\Z'),
"DTEND:".$end->setTimezone(new DateTimeZone('UTC'))->format('Ymd\THis\Z'),
"UID:{$uid}",
"CLASS:PUBLIC",
"PRIORITY:5",
"DTSTAMP:".gmdate('Ymd\THis\Z'),
"TRANSP:OPAQUE",
"STATUS:CONFIRMED",
"SEQUENCE:0",
"LOCATION:123 Any Street",
"BEGIN:VALARM",
"ACTION:DISPLAY",
"DESCRIPTION:REMINDER",
"TRIGGER;RELATED=START:-PT15M",
"END:VALARM",
"END:VEVENT",
"END:VCALENDAR"
);
$calendarBase64 = base64_encode(implode("\r\n",$calendarLines));
//ensure we don't have lines longer than 70 characters for older computers:
$calendarResult = wordwrap($calendarBase64,68,"\n",true);
$emailLines = array(
"--{$boundary}",
"Content-Type: text/html; charset=\"iso - 8859 - 1\"",
"Content-Transfer-Encoding: quoted-printable",
"",
"<html><body>",
"<h1>Hello World</h1>",
"<p>This is a calendar event test</p>",
"</body></html>",
"",
"--{$boundary}",
"Content-Type: text/calendar; charset=\"utf - 8\"; method=REQUEST",
"Content-Transfer-Encoding: base64",
"",
$calendarResult,
"",
"--{$boundary}--"
);
$emailContent = implode("\n",$emailLines);
$headersResult = implode("\n",$headers);
mail($toEmail, $summary, $emailContent, $headersResult );
echo("<pre>".htmlentities($headersResult)."\n\n".htmlentities($emailContent)."</pre>");
echo("<br /><br />");
echo("<pre>".base64_decode($calendarResult)."</pre>");