Strange time zone adjustment on MIME email

This is nothing too dramatic, but curious nonetheless.

Just received an email (a response from an abuse desk about a confirmed spammer kill - not relevant this, but it makes me happy and I want to share it), and it appears to be dated 12 hours in the future.

I thought it odd that the email software used by the abuse desk of a well run ISP could be misconfigured, so I took a look at the MIME source of the message (slightly munged below to protect the innocent).

Received: from example.com ([192.168.1.1])

      by my.domino.host (Lotus Domino Release 6.0.1CF1)

      with SMTP id 2003042415183389-5834 ;

      Thu, 24 Apr 2003 15:18:33 +0100 

Received: from example by example.com with scanned-ok (Exim 3.13 #1)

	 id 198hYY-000AWb-00

	 for [me]; Thu, 24 Apr 2003 15:18:34 +0100

Received: from someplaceelse by example.com with local (Exim 3.13 #1)

	 id 198hYU-000AVw-00

	 for [me]; Thu, 24 Apr 2003 15:18:30 +0100

From: “ISP Abuse Team” abuse@isp.example

To: Christopher W Linfoot <[me]>

Subject: Re: spam

Date: Thu, 24 Apr 2003 15:18:30 BST

Note that the time stamps on all received headers are within a few seconds of 15:18:30 +0100 (eighteen minutes past three in the afternoon, UK daylight saving time). This was the correct time at the time the message was delivered.

The “Date” header is also 15:18:30, but says “BST” where it should say “+0100”. I believe Notes uses the date header to display the message received date, when it is available.

The question (of no great significance to me right now but I confess, I am intrigued) is, why does the Notes client display this date as 03:18 tomorrow? It has somehow interpreted “BST” as UTC +1300, not UTC +0100.

Just thought it a bit arbitrary that Notes would take this as +1300 as opposed to any other value, though the true misbehaviour is obviously in the sender’s mail client as I don’t think “BST” is a valid for an RFC2822 time zone (http://rfc.net/rfc2822.html#s3.3.)

Subject: Strange time zone adjustment on MIME email

the sender obviously meant BST as ‘British Summer Time’, but notes interpreted it as ‘Bering Standard Time’. in general BST is eleven hours behind UTC, but when “UTC” observes daylight savings BST is twelve hours behind.

so if it is 15:18 Bering Standard Time (i.e, 03:18 P.M.) at the sender’s locale on a given day when the message is sent, then it is also 3:18 UTC (i.e, 03:18 A.M.) at the receiver’s locale, but the next day.

of course, BST could also be interpreted as Brazilian Standard Time… gAck.

in short, the isp’s app is misconfigured or incapable of sending proper time zone indicators.