Small clarification on Send mail to outlook?

Hi experts,

is  it mandatory to maintain E-mail address in both SU01 as well as PA30  to send mails to outlook??

or

when we will go for to maintain  E-mail address in SU01 to send mails to outlook??

When we will go for to maintain E-mail address in  PA30 to send mails to outlook??

Thanx

Seetha