You may find there are times when your email is returned or "bounced back" due to the server IP or even your own IP being on a blacklist. This isn't necessarily because masses of spam email has actually been sent out as there are many reasons for blacklisting, and below are just a few.
A mailing trojan/malware/virus on the system or device the email is being sent from will result in an IP being blacklisted, so please scan your system/device regularly for any suspicious files. Updating your virus scanner beforehand will ensure the latest virus definition files are used during scanning.
Sending mail to out-of-date email addresses can cause an IP to be blacklisted. This is usually determined as sending to email addresses that have not been functional for 2 years, but it may be less.
The recipient inadvertently marking the mail they have received as "spam" in their email client - such as Outlook, Apple Mail etc - even if the email is genuine, may cause an IP to be blacklisted.
Keywords detected in the subject and content of mail can be marked as "spam like activity" by some spam filters and lead to blacklisting as a consequence, even though the mail is legitimate. Such keywords can include "free," "win," "cash" etc. In addition to this, using full upper case LIKE THIS in emails can also be a flag for spam filters.
A hidden mailing trojan/malware/virus in your website files due to compromise can cause unsolicited email to be sent out through our server also. As most website compromises are due to outdated scripts/software, please ensure you update your site files and all scripts including any themes and plugins regularly to help prevent this happening.
While we take spam seriously at QiQ and try to prevent blacklisting, please note that we have no control over what blacklist our mailserver IP may appear on and we can only request removal - we cannot stop blacklisting. There are many other servers not associated with QiQ that may also experience blacklisting such as Google, Microsoft, Yahoo and more, and it is an unfortunate consequence of shared server platforms in general.
Additionally, we often find that client's own IP addresses - provided by your ISP - are blacklisted. If this is the case you will need to request removal from the relevant anti spam filter that is blacklisting your IP, or seek advice from your ISP.
If you experience blacklisting, please provide a copy and paste of the full bounce back message to QiQ Support HERE so we can investigate further for you.