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.
The Postal Service offers a service called Business Reply Mail (BRM). By opening an account with the local Post Office, a business may supply their customers with return envelopes or labels. This allows customers to send a reply via First-Class Mail or Priority Mail. The business pays the postage and a per piece fee only for the pieces returned.