Should we ban the word “lady” from our vocabulary?

I recently received an email from my boss, sent to the organization, telling us why the term "lady" or "ladies" should not be used.  For full disclosure, we work at a women’s shelter where feminism is accepted and encouraged. 

I agreed with the email and I do try to avoid using the term whenever possible.  However, I find myself typing emails and starting them with "Hello ladies" because it seems more personable than just, "Hello."  I usually catch myself and delete the offending term before I send the email.  But what of calling a group of women "ladies"?  As in, "The church ladies are coming over for dinner" or "The ladies took care of all of the fundraising" ??

The term is loaded, to be sure.  I wouldn’t find myself writing "Hello gentlemen" to a group of men (or would I?). But can I address a group of professionals "Ladies and Gentlemen"????  I don’t know.

I’m just wondering what everyone in this community thinks about the use of the word and also what you all have done to stop yourself from using words like these that we all have gotten so used to using.