This depends on whether you have a Gmail or Outlook account or if you have added your professional email account through an SMTP/IMAP connection.
Gmail or Google Workspace
As Campaigns directly integrates with your Gmail or Google Workspace account, the email signature is automatically retrieved from it.
The signature can be edited in your Gmail settings.
Outlook or Microsoft 365 Business
As the signature cannot automatically be retrieved from your Outlook or Microsoft 365 Business account, you will need to add it manually to the content of your emails and campaigns in Hunter.
SMTP/IMAP Connection
If you have a paid plan you can connect your professional account through SMTP/IMAP. The signature for SMTP/IMAP email account connections can be edited directly in Hunter, by clicking on "Edit" in the email account settings in Campaigns.
You also have the option to customize the signature by inserting links and images.