There is no separate "signature" or "P.S." feature. Both are ordinary text you add inside the email body using the same drag-and-drop composer you use for the rest of your message.
Adding a P.S. line
Open your email campaign and scroll to the Content step.
In the design editor, drag a Text block from the left panel into the position you want below your main message.
Click the block to open the inline text editor and type your P.S. line (for example,
P.S. Your last gift of {lastDonationAmount} made a real difference.).You can use any of the available merge fields inside the text block, such as
{firstName}or{lastDonationAmount}, to personalize the line per recipient.Save your draft as usual.
If you are using the plain text mode instead of the design editor, click at the point in the text where you want the P.S. to appear and type it directly.
Adding a sender signature
A signature is just a text block (or combination of text blocks) placed at the bottom of the email. The steps are the same as above:
Add a Text block below your closing line.
Type your name, title, and any other text you want to appear.
If you want the sender name to match the recipient's assigned contact, use
{firstName}in the greeting above it but type the sender name as plain text in the signature block, since there is no merge field for the sender's own name.
Tips
Drag the block to reorder it if you need the signature or P.S. to appear in a different position.
Use the text formatting toolbar inside the block to adjust font size, style, or alignment.
The unsubscribe link block is fixed at the bottom of every campaign by default. Your signature and P.S. will appear above it.