Here is a Python solution using regular expressions to extract the valid email addresses: ```python import re text = "Contact information:\n1. John Doe - john.doe@example.com\n2. Jane Smith - jane@smith-family.net\n3. support@company.co.uk\n4. info@subdomain.example.org\n5. Invalid email: not.an.email.com\n6. Another invalid: @missing-username.com" emails = re.findall(r'[\w\.-]+@[\w\.-]+', text) print(','.join(emails)) ``` When you run this script, it will output: ``` john.doe@example.com,jane@smith-family.net,support@company.co.uk,info@subdomain.example.org ```