Outlook

Tools > Options > Accounts

Mail > [Properties]

Servers

Outgoing mail (SMTP): rsxxx.realsender.com

Outgoing Mail Server

[x] My server requires authentication

[Settings…]

Outgoing Mail Server

[x] Log on using

Account name: (the one we sent you)
Password: (the one we sent you)

[x] Remember password

[OK]

Advanced

Outgoing mail (SMTP): 25
[x] This server requires a secure connection (SSL)

[OK]