When considering the cost of roofing materials, many people take into account just the shingle prices. This is incorrect, as a roof made just of roofing shingles will not work. You also need to consider all the accessories that are included in a complete roof system.
The differences between emails and letters is that, emails are send electronically and arrives faster to the person that you are sending it too, while in the other hand letters takes a little bit longer to arrives to the person and can be lost from the mailing company especially whens sending it overseas also it cost money.
Postal Mail -- Respond Within Five Days. Five business days is the standard business letter response time. Postal mail can take two to three days or longer to reach even a local client. A further delayed mail response can indicate to a customer that your company is disinterested in his business, or worse, unprofessional and sloppily run.