The last line of the letter says "you are encouraged to immediately contact code enforcement to discuss resolution."

There is an exclusion for your primary residence which is found in sec 121 of the IRS code. 

You can exchange in and out of any state. 1031 Exchange is federal tax code. 

This will help you with your 1031 exchange "case" with the IRS. 1031 Exchanges are a federal IRS tax code instance and so anyone in the US can help with a 1031 exchange but @Dave Foster is one of the best!

It must meet the requirements per the building code IRC (I think Massachusetts follows a modified version of the IRC) you must provide the required amount of light, air/ vent, and egress.

If you do not then you can ask realtors, property managers, other investors as to what zip codes are the bad areas and stay away.

But your land use codes may be different. 

Under the California Business and Professions Code, it is required in the sale of residential property of not more than four units that the listing (or other document that initially establishes the broker's right to a commission, or changes the commission rate) contains the clause: "Notice: The amount or rate of real estate commissions is not fixed by law.

Any advice on the zip code I've mentioned?

Use that information to determine what you need to do to compete with them, and to make your house just a little bit nicer for the price range.In addition, you'll want to ensure that any safety issues, code issues or issues that would cause problems with your buyer getting a mortgage should be fixed first and foremost.