Bizarre Yahoo-mail bug/policy
[This paragraph added later: the information below may not be accurate. See next entry. Leaving this entry in place anyway, but don't panic; just try sending mail to and/or from your Yahoo account and see if anything gets changed. If it doesn't, then the report mentioned below must be either wrong or outdated.]
Warning to anyone who uses Yahoo-based mail: Yahoo may be changing the text of messages sent to you, without telling you about it.
According to this news.com article, Yahoo Mail has been changing anything that looks like a scripting-language keyword into a more innocuous "synonym." For example, if someone sends you a message containing the word "mocha," Yahoo will replace that with "espresso." The keyword "eval" is bizarrely changed to "review" even when it appears as part of another word, so "evaluate" is transformed into "reviewuate" and "medieval" into "medireview."
Needless to say, I find this practice reprehensible, especially since (a) Yahoo doesn't tell users that they're doing it, and (b) as noted in the article, all other free-email providers have found more effective ways of achieving the same security goals, without changing the text of email.
Anyway, if you use Yahoo Mail for anything involving proofreading, be careful.
(It's not clear to me from the article, btw, whether this applies to both incoming and outgoing mail. But since Yahoo claims to be doing it to protect their customers, I'm guessing it applies only to incoming mail.)
My guess is that public outcry will force Yahoo to fix this immediately. Still, if you use Yahoo Mail, couldn't hurt to join in that public outcry by writing to Yahoo about it.