Some of the mails might be affected because the data centre being inaccessible. This all depends on the type of spambox your domain is pointing to. We have two different spamboxes sitting at two different data centres. For all mails going through the spambox at the data centre that is having an issue mails will be affected and they will all bounce back to whoever is sending you an email.
For a temporary fix you just need to add another mx record and set the content to mail.domainname.tld and make sure the priority is lower than the spamboxes priority so that mails can go through mail.domainname.tld until the issue is fixed.
NB:Outgoing mails will not be affected. Only incoming mails will be affected.