I am developing a DB for bulk mailing

The requirements are

1. There are categories and subcategories. These two have many to many relationship. ie. One category can have 0 or many subcategories and one subcategory can exist in more than one category.

Ex.

Textile
Accessories
Garments
Leather
Footwear
Accessories
Garments

Manufacturing

Automotive
Aerospace
Footwear

Education
Schools
Colleges
Training institutes

Hospitality

etc.

A person ( email id) may belong to more than one category and subcategory

ie.

rana@hotmail.com may belong to

Textile - Garments
Textile - Accessories
Leather - Garments
Education - Trainig institutes

There will be a set of newsletters which has to be sent to the clients.Care has to be taken that eventhough rana@hotmail.com exists in more than one category the same newsletter( Ex. newsletter1) should not be sent to him more than once. The scenario is first newsletters will be sent to Textile category which includes rana@hotmail.com .Second time when the same newsletter is sent to the category Education that should send mails to all email ids in that category excluding rana with the possible warning message that the newsletter has already been sent to rana@hotmail.com.And finally the system should have an detailed report of the mails and newsletters sent.

The current DB design is

category table

cat_id ------------------PK
category ---------------varchar(200)

Subcategory table

sub_cat_id ------------PK
sub_cat ---------------varchar(200) PK


emails Table

email_id ------------PK
name
address
etc...
lists (to which he belongs to)

lists in emails table is stored as
//cat_id1-sub_cat_id1//cat_id2-sub_cat_id2//cat_id3-sub_cat_id3//


newsletter table

news_id ------------PK
newsletter ( path to the newsletter file is stored )


reports Table

email_id
sent_on
sent_items

sent_items is of the format
///path of newsletter1-Date Sent///path of newsletter2-Date Sent///

I would like to know about the flaws and the suggestions on improving the design.

Thanks in advance

Sorry these are the category and subcategory details

Textile----Accessories
Textile----Garments


Leather----Accessories
Leather----Garments
Leather----Footwear

Manufacturing----Automotive
Manufacturing----Aerospace
Manufacturing----Footwear

Education----Schools
Education---- Colleges
Education----Training institutes

Hospitality----no subcategory

etc.