gmail is replacing outgoing email address when using CaseSensitive Froms

I have several email address set up as valid outgoing emails on one of my Google Apps account.
Today I noticed, by getting a bounce to a Mailinglist, that the outgoing email was wrong.
I did a few tests, and noticed that what causing it was, the email client profile for that mailinglist having a Case Sensitive email address on the From field.

I.e, it was Laconica@mydomain.com
using laconica@mydomain.com works fine.