searching email with regular expressions

[Nataraj]

Do imap servers like dovecot have the capability to search on regular 
expressions?  What about specific email clients.

http://en.wikipedia.org/wiki/Comparison_of_e-mail_clients seems to 
indicate that evolution has some type of support for regular 
expressions.  If so, I don't see how to use it.  Any ideas?  What about 
thunderbird or other email clients.

Thank you,
Nataraj