Unable to get a mail from an address outside thecompany

Unable to get a mail from an address outside thecompany

We are facing a issue with our E-Mail. We are unable to get E-Mails sent from an ID outside our company. i.e. IDs that dont have @ inventrom.com from last 3 days.

Please help us regarding the same as it is urgent.

I am unable to log in the support page so directly posting here