Ask yourself this question: Will the registrant email you use for domain registrations exist even if you l were not in the company anymore?
The golden rule is to ensure that the contact email is not dependent on a specific employee and is a corporate email. It is rare that an employee stays with a company forever, so the WHOIS (official registrant data) contact email has to outlive any person. You can always update your admin or billing contact email with your registrar (GoDadddy, EuroDNS, European Domain Centre etc.), but the WHOIS email can only be changed via the local hostmaster (DENIC, AFNIC etc.).
Here are 3 scenarios where an inactive or misspelled contact email causes problems:
1. When making a registrar transfer the country hostmaster uses the email in the WHOIS to send an email to the registrant. This email has to be confirmed in order to complete the transfer. In many cases this email does not exist anymore. This would have been avoided if a generic email was used like info@, support@ or it@. To change the email is not easy, as it has to be accepted by the contact person, who most likely is the former employee.
2. A misspelled contact email can have dire consequences. Some years ago an online betting agency had misspelled the domain in their contact email. A 3rd party observed this, registered the free domain, created the email and transferred the other domain to him. The email controls the ownership of the domain !
2. Companies can change name and expire unused domains. But what if an expired domain formerly was used as contact email for current domains. I repeat, the email controls the ownership, and someone can snatch up the company´s domains as referred to the example above.
The method used in 2. and 3. is of course illegal, but any company losing their online identity overnight is willing to pay thousands of Euros to the thief to get back the domain right away, instead of trying to claim it back legally.
How often does this happen? Often, but no company is interested in ending up in the media for not having 100% domain control, so it is better to settle quickly and move on. It is not too late for you however. Check your WHOIS data today.