Spam is still one of the biggest inconveniences on the internet. Not only incoming spam causes problems but inadvertently sending spam or seen to be sending spam as well. Spammers regularly hack servers that are subsequently abused for sending spam. Most hacks take place because updates to websites are not installed in time or because weak passwords are cracked. We recommend you to install updates on time and apply proper password management to your environments.
Another, less obvious, way that spam can unexpectedly cause problems is by the use of so called forwarding rules. When the mail server is configured to forward all incoming mail to an email service like Hotmail, then all emails including all spam will be forwarded on. Hotmail subsequently sees a lot of spam coming in from your IP address. The service will then refuse emails from your IP address and the IP can also get onto generally used spam lists. Because of this we strongly discourage the usage of unfiltered forwarding to email services.
In order to reduce the disruption caused by spam more and more email services implement strict rules surrounding incoming emails. The drawback of this is that many users that are not sending spam themselves can still experience when sending emails, because they do not satisfy these strict rules.
Many of these rules are technology based and are related to configuration settings that indicate if a server is really allowed to send email for a specific domain. Examples of this type of settings are SPF and DKIM. SPF means Sender Policy Framework; a configuration in the domain definition that indicates which server is responsible for sending email for that domain. DKIM means DomainKeys Identified Mail, this is an authentication system that allows organisations to take responsibility for the processing of email for a specific domain. Other settings that can be checked are the so-called reverse DNS settings. These allow an IP-address to be converted to the relevant server name. This is especially important for IPv6, since setting the IPv6 reverse DNS is often forgotten when configuring the DNS.
Your engineer will be able to help you to correctly configure all of the above, so you can send and receive mail more easily.