Reprinted from TidBITS by permission; reuse governed by Creative Commons
license BY-NC-ND 3.0. TidBITS has offered years of thoughtful commentary
on Apple and Internet topics. For free email subscriptions and access to the
entire TidBITS archive, visit http://www.tidbits.com/


          Yahoo-Backed POP Connections Cause TidBITS Formatting Error

   Adam Engst

   A few months ago, I wrote about a quirky, sporadic problem that readers
   would report to us on occasion (see '[1]LittleBITS: TidBITS Formatting
   Bug, Ransomware Protections, More OCR in Images,' 15 November 2021).
   For these readers, an article in the TidBITS issue would occasionally
   be formatted as a column of text that's a single character wide. I
   tracked down the cause of each problem to corruption in the CSS styling
   for the issue that caused style="padding: 0.25em" to change to
   something like style="padding:25em". That corruption transformed a
   slight indent into a massive one.

   If the problem had happened once, I could have chalked it up to a
   communications error somewhere along the way. But it was happening to
   multiple users, and some of them saw it multiple times, so there had to
   be some other commonality.

   Our support whiz Lauri Reinhardt and I received reports from multiple
   ISPs, but upon closer examination, they weren't as separate as they
   might have seemed. That's because Verizon bought AOL in 2015 and
   acquired Yahoo in 2017. At some point, Verizon transitioned both
   aol.com and verizon.net email accounts to the Yahoo Mail backend.
   (Yahoo and AOL were [2]acquired by Apollo Global Management in May 2021
   and are no longer part of Verizon.) At some point, Frontier
   Communications also entered into a partnership with Yahoo for its
   email, adding frontier.com and frontiernet.net to the domains that
   relied on Yahoo Mail behind the scenes.

   That was the first piece of the puzzle, but we have over 2100
   subscribers from those domains plus yahoo.com, so if that's all there
   was to it, we would undoubtedly be receiving more reports of the
   problem. After some back and forth with the people who reported the
   error, I figured out the remaining piece of the puzzle'they all used
   POP to download their email from the server. The vast majority of
   Internet users use the server-focused IMAP protocol for accessing email
   because it makes working on multiple devices much easier, but POP
   remains available at many ISPs.

   TidBITS reader Bill Gruber provided a possible explanation. He had
   encountered a similar problem with periods disappearing and discovered
   that a line that contains just a period would terminate the
   transaction. (I can't quickly parse POP3's [3]RFC 1939, but there is
   mention of CRLF.CRLF terminating a multi-line response.) Bill found
   that some ISPs were incorrectly stripping leading periods from a
   wrapped line, presumably to protect against an inadvertent termination.
   So if a line were broken such that it started with a period, the ISP
   would strip that period. The problem was impossible to reproduce
   because email headers are of random lengths, so the point where a line
   would be wrapped could change on every send. Needless to say, removing
   periods can play havoc with formatting, as we experienced, and Bill
   pointed out that it could be problematic in other ways, such as
   changing an instruction to administer .25 ml of medicine to 25 ml.

   If POP were widely used and if it was easy to connect with Yahoo Mail
   support, I'd report this bug. (Here's an example of the difficulty of
   connecting with Yahoo support. Earlier this week, an acquaintance's
   email account was compromised, and the attacker sent me multiple emails
   trying to fool me into sending him an Amazon gift card. After the first
   message, he tried to redirect our conversation to a similar-looking
   Yahoo account that wasn't controlled by my acquaintance. After alerting
   my acquaintance via a text message, I looked for some way to report
   this obvious abuse to Yahoo but could find no appropriate support
   channel.)

   Instead, for those who experience this problem, I suggest you switch to
   IMAP. If that's not something you wish to do for technical or
   philosophical reasons, you can read TidBITS articles that get corrupted
   in email on our Web site instead'just click the article title in the
   issue to load it in your browser.

References

   1. https://tidbits.com/2021/11/15/littlebits-tidbits-formatting-bug-ransomware-protections-more-ocr-in-images/
   2. https://www.theverge.com/2021/9/2/22653652/yahoo-aol-acquired-apollo-global-management-private-equity
   3. https://www.ietf.org/rfc/rfc1939.txt

.