You cannot format the email text beyond how the text is capitalized unless you use an email plug in in place of Send Mail.
With the send mail dialog open, click the black arrow to the right of the "Body" text box and you can select a calculation option where a calculation can combine values with literal text and your fields to produce the message you want to see in the email body.
Thanks for the reply,....When i clicked the back arrow and select the customer full name from the customer table, the name does not show up in the email body when the email is retrieved. Is there any additional thing to do to the field name?
Welcome Customers::Full Name
You should use the calculation option to produce an expression such as:
"Welcome " & Customers::Full Name
And your "context"--which record in which table occurrence, as determined by what layout is current will determine what value, if any is produced by the reference to this field named Full Name from a table occurrence named Customers.