To extract all valid email addresses from the given text and return them in a comma-separated list without spaces, you can use regular expressions to find the email addresses and then concatenate them into a single string. Here's the Python code to accomplish this: ```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""" email_pattern = r'\b[A-Za-z0-9._%+-]+@[A-Za-z0-9.-]+\.[A-Z|a-z]{2,7}\b' valid_emails = re.findall(email_pattern, text) emails_list = ','.join(valid_emails) emails_list ``` Output: ``` john.doe@example.com,jane@smith-family.net,support@company.co.uk,info@subdomain.example.org ``` Explanation: 1. We import the `re` module for working with regular expressions. 2. We define the `text` variable containing the contact information text. 3. We define the `email_pattern` variable using a regular expression to match valid email addresses: - `\b`: Matches the position where a word starts - `[A-Za-z0-9._%+-]+`: Matches one or more characters that are alphanumeric, dot, underscore, percent, plus, or hyphen - `@`: Matches the '@' symbol - `[A-Za-z0-9.-]+`: Matches one or more characters that are alphanumeric, dot, or hyphen - `\.`: Matches a dot ('.') - `[A-Z|a-z]{2,7}`: Matches 2 to 7 characters that are uppercase letters (case-insensitive) - `\b`: Matches the position where a word ends 4. We use `re.findall()` to find all occurrences of the `email_pattern` in the `text` variable and store the results in the `valid_emails` list. 5. We use `join()` to concatenate the elements of the `valid_emails` list into a single string, separated by commas and without spaces, and store the result in the `emails_list` variable. 6. Finally, we print the `emails_list` output. Note: This regular expression pattern assumes a basic format for valid email addresses and may not cover all possible variations of valid email formats. You can adjust the pattern as needed for your specific requirements.