How can I prevent my domain from being blacklisted due to an infected employee's computer or scraping contact information?

Email marketer from Email Marketing Forum shares that educating employees about phishing scams and safe computing practices can minimize the risk of malware infections that lead to outbound spam.

Marketer from Email Geeks says if you have multiple relay instances outside of your org, the reputation of each relay server can be taken into account and suggests setting your MTA to strip out those internal headers (try hide-message-source, and remove-header in PMTA).

Email marketer from Marketing Over Coffee shares that implementing CAPTCHA on signup forms prevents bots from adding scraped or fake email addresses to your list, helping to maintain a clean and legitimate subscriber base.

Marketer from Email Geeks advises to get your MTA to strip out the client connecting IP from the outbound messages (replace it with 127.0.0.1) and then tell them you reformatted the offending laptop.

Email marketer from StackExchange answers that implementing DMARC (Domain-based Message Authentication, Reporting & Conformance) can help prevent domain spoofing and unauthorized use of your domain for sending spam, protecting your reputation.

Marketer from Email Geeks explains that any relay servers will add "received" headers to your email, and if any of those relay IP's appear in blocklists then delivery of your email may be affected. The local email setup affects this (i.e. does it go from outlook on a laptop, to an exchange server, to a relay server etc.).

Email marketer from Sendgrid suggests using a dedicated IP so that if you do get any sort of bounce or block, this has zero impact on other businesses or domains. This allows for a quicker resolution to IP/Domain blocks.

Email marketer from Email Deliverability Blog explains that regularly monitoring your domain's reputation using tools like Google Postmaster Tools can help you identify and address deliverability issues before they result in blacklisting.

Email marketer from Cybersecurity News says running regular malware scans on all company computers, especially those used for email communication, to detect and remove any infections that could be used to send spam is important to prevent blacklisting.

Email marketer from Mailchimp Resource Centre explains using double opt-in requires new subscribers to confirm their email address before being added to your list, which ensures that all subscribers are legitimate and actively want to receive your emails.

Email marketer from Reddit responds that regularly cleaning your email list to remove invalid or unengaged addresses can reduce the risk of sending to scraped addresses and triggering spam traps.

Marketer from Email Geeks advises that it's not best practice for filters to look at any IP other than the one that initiated the SMTP connection, as 'Received from:' headers contain a mix of RFC1918 addresses and dynamically assigned IPs from ISPs that shouldn't be associated with a domain or sender.

Expert from Email Geeks says scraping email addresses and sending unsolicited mail to people who never asked for it and for whom it brings zero value to the recipient is problematic and will get blocked. Such companies prohibit unsolicited email.

Expert from Email Geeks suggests looking for the IP address in SMTP records to trace where it comes from, and most importantly, determine which authenticated user it is.

Expert from Spamresource.com responds that monitoring employee computer activity and restricting scraping or external tools could limit the scope of any potential blacklisting issues. This includes web-filtering, data loss prevention and anti-virus.

Expert from Email Geeks says that scraping email addresses from google search results and mechanically harvesting those addresses, then sending boilerplate mail out to them, without their being any consent or implied relationship is what makes it spam, regardless of volume. Even scraping role addresses is spam.

Expert from Email Geeks says that in the US, if you scrape an address and fail to abide by CAN SPAM (and 90% of the messages I get fail to abide by CAN SPAM) you're not only breaking the law but you have treble penalties.

Expert from Word to the Wise states that staff training on security best practices, including what to look for in a phish, or a suspect link or an unexpected email attachment, will help make the business more secure.

Expert from Email Geeks suggests that the issue could be an employee infested with malware, blasting it out through your smarthost. He recommends going through mail logs, cross-referencing the timestamp and given IP address to identify the authenticated user, then take their laptop away and look at it.

Expert from Email Geeks believes that the employee got infected with something and they're spewing crap out of your smart host, and recommends contacting IT Security and telling them.

Expert from Email Geeks says that MIMECast gave enough information to identify the user involved, but they might give you more if you can't find it from that.

Expert from Email Geeks explains that the IP address that Mimecast provided belongs to the machine that is sending out the malware and is information to help track down the infected machine.

Expert from Word to the Wise suggests setting strong password policies as part of a holistic approach to security. This includes setting minimum length, complexity and using MFA.

Expert from Spamresource.com shares using a blocklist monitoring service. Some blocklist services provide notification options or offer commercial monitoring products so they can notify a customer directly of listing issues.

Documentation from Spamhaus shares that having a clear and easily accessible unsubscribe process is essential for compliance and preventing blacklisting due to scraping and unsolicited email complaints. Make sure to honor all unsubscribe requests immediately.

Documentation from Cisco says network segmentation can limit the damage a virus can do. By separating parts of the network, they can only send spam through the segmented network, so it is easier to detect and limit damage.

Documentation from Google explains that securing user accounts with strong, unique passwords and enabling 2-Step Verification can help prevent unauthorized access that could lead to an infected computer sending spam and getting your domain blacklisted.

Documentation from Microsoft Learn states that monitoring outbound email for unusual activity and implementing limits on the number of emails users can send can help identify and contain compromised accounts before they cause domain blacklisting.

Documentation from RFC explains that Implementing SPF (Sender Policy Framework) records can help prevent unauthorized use of your domain by specifying which mail servers are authorized to send email on your behalf. The SPF record should be as tight as possible, and if you use 3rd party senders list these instead of A records if possible.