user@domain-name incorrectly expands to a twitter user (BB-7073)

When replying to an issue via email, from the address "michael@smart-africa.com", the following text is displayed in the issue tracker for my comment:

(Reply via mich...Gábor Békefi-africa.com):

This indicates that the @smart portion of my email address has been expanded to a Twitter username, which is incorrect.