Postal Service Vs. Email (How are they different and similar?)

There are many questions to what the difference is between the Postal Service and Email. Now the most general answer would be something like "Well, the Postal Service sends Physical mail such as letters, and packages, while email sends similar things, however they are Digital, not Physical". I probably could've worded this in a much more simpler and shorter but, what the heck.
This is true, but there are more in-depth things that make them even more different from one another.
Another question would be, How are they similar to one another? Again, the most general answer would be "They both send mail and you get mail." Now this answer is much simpler and again, most true. Also like the differences, there are more in-depth things that can make them more similar.

Lets start with the differences. Now I will only go through a few so this isn't so lengthy.
First, the most general, Postal Service sends and receives physical mail while e-mail sends and receives digital or electronic mail, as the "e" in e-mail stands for Electronic. Next, The Postal Service have mailmen to deliver your mail to your mailbox. Email however, does not use mailmen, but mail servers and such that receive mail to send to send to the receiver's inbox, or digital mail box in other words. The other difference is that when your internet at home, or where ever you are goes down, the mail that is being sent to you will still arrive in your inbox, even if you can't access it. However, if something were to happen at the postal service or in the event of a disaster, then there is a chance that you won't be getting that mail you were waiting a few days for even if you check that mailbox extensively.

Now to the similarities.
When sending a letter to someone, you really only need to get the address to where the letter is going to correct. That means the name to who you are sending it to doesn't really even matter. It's just there to let the receiver know that it is for that particular person. For Email, you also need to get the Address, or in this case, the Email Address correct to have it go to the person you want to send it too. And like a physical letter, the Name or "Subject" in this case, doesn't matter. However, it does help filter out mail and allow the receiver to find it quickly. Another similarity would be that if you are sending a letter to someone, both digitally and/or physically, it is still a letter. Okay so some people see letters as a physical object, I say some, not all, either handwritten or printed text, such as a resume or a letter from your school. However, the same text is also considered a letter if it is digital too. You know when your typing something and when you are going to send it the send button is like a letter? Well, that might not be the case with some if not most email's now like Gmail or Yahoo! Mail, but it is still representing a letter, just digitally. Heck, if you still don't think it is, then just print it out. Boom. Letter.