````python import re text = """ Contact information: 1. John Doe - john.doe@example.com 2. Jane Smith - jane@smith-family.net 3. support@company.co.uk 4. info@subdomain.example.org 5. Invalid email: not.an.email.com 6. Another invalid: @missing-username.com """ emails = re.findall(r'\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Z|a-z]{2,}\b', text) email_list = ','.join(emails) print(email_list) ```` This Python script uses regular expressions to extract email addresses from the given text. Here's how it works: 1. The `text` variable contains the input string with a list of contact information, including valid and invalid email addresses. 2. The script uses the `re.findall()` function to search for all email addresses within the `text` string. 3. The regular expression pattern `\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Z|a-z]{2,}\b` is used to match the email addresses. Let's break down the pattern: - `\b`: Matches a word boundary to ensure the email address stands alone. - `[A-Za-z0-9._%+-]+`: Matches the username part of the email address, which can contain letters (both uppercase and lowercase), digits, dots, underscores, percent signs, plus signs, or hyphens. - `@`: Matches the "@" symbol. - `[A-Za-z0-9.-]+`: Matches the domain name part of the email address, which can contain letters, digits, dots, or hyphens. - `\.`: Matches the dot (.) before the domain extension. - `[A-Z|a-z]{2,}`: Matches the domain extension, which consists of at least two letters (uppercase or lowercase). 4. The `re.findall()` function returns a list of all email addresses found in the `text`. 5. The script then uses the `','.join()` method on the `emails` list to join all email addresses together into a single string, with each email separated by a comma, without spaces. 6. Finally, the script prints the resulting email list. For the given input text, the output will be: ``` john.doe@example.com,jane@smith-family.net,support@company.co.uk,info@subdomain.example.org ``` The script successfully extracts the valid email addresses and returns them as a comma-separated list without spaces.