Question: How can I manipulate the "from" field in an email and make the "to" user see something different then the actual.

Example: 

really from 

```
From: TStamper@yahoo.com

```

but they see

```
From: Tremayne "Top Dog" Stamper

```

I've heard its from manipulating SMTP, but really not sure how accurate that is or how it can be done

Answer: 
The "really from" address comes from the "from:" dialog in the SMTP conversation.

The "fake from" comes from exploiting the common practice in email clients of displaying the various header fields as laid out in the Data portion of the SMTP conversation. For instance:

```
# telnet mail.example.com 25
Connected to mail.example.com.
Escape character is '^]'.
220 mail.example.com ESMTP Postfix
helo fakeserver
250 mail.example.com
mail from: real@example.com
250 2.1.0 OK
rcpt to: real@example.com
250 2.1.5 Ok
data
354 End data with <CR><LF>.<CR><LF>
from: fake@example.com
to: you@example.com
subject: This is a subject
This is the body.
.
250 2.0.0 Ok: queued as 90D0F95A06
quit
221 2.0.0 Bye
Connection closed by foreign host.
#

```

If you had left out the "from:" and "to:" lines in the Data portion, it would have displayed the actual envelope sender and recipient.

Note that these sorts of tricks are often looked for by spam filters, and will certainly not make you any permanent friends. Also, this doesn't work on all mail clients (just the most common ones).
Yes, it's by manually setting SMTP headers and is trivial to accomplish. Google it. But don't get caught spamming......