problems with distribution email

Hi!  The McAfee Waterloo Toastmasters Club has also been having issues with the DL .  For about a week, the messages I've sent haven't been going through to our members.  Thanks for any help you can give - we use our member DL often, and we are missing it. 

 I have been getting these error messages from my company's email system:Your message couldn't be deliveredThe message you sent to This email address is being protected from spambots. You need JavaScript enabled to view it. couldn't be delivered due to: Recipient server unavailable or busy.Further informationConnection timed out (Connection timed out)If you sent this message to multiple addresses, you'll receive a notification like this for every one that didn't arrive.

Your company uses an email supplier that has frequently spammed FTH and their email servers are blocked.

If you can tell exactly which single IP address your company will send FTH email on I will unblock it but not the long list of mimecast email server IP.

Thanks, Brian, for the response.  

Could you please tell me what type of spam is causing the problems?  I'd like to understand the issue better, if at all possible.  Thanks!

Any​​​thing that is not requested is spam.FTH gets 100,000 spam a month. We don't analyze it we just block it at the highest level possible. Usually by data center or supplier