November 20, 2019 – 11:00am – We have received reports indicating that we have been blacklisted by Barracuda’s spam system. Barracuda’s spam filters are in wide use, so this affects many recipients. We are working to find out the reason for the blacklisting and are asking to be removed. These type of listings take a bit of time as not all internet service providers and mail server operators synchronize their lists at the same time or in the same interval. In the mean time, if you have sent email to a recipient and received a bounce, you can ask the recipient to put you on their whitelist so that your email will flow until this is resolved.
A sample bounce message will contain this information:
Remote host <IP address> does not like recipient <recipient email address> Remote host said: 554-Service unavailable; Client host [mail.internetpro.net] blocked using 554-Barracuda Reputation; 554 http://www.barracudanetworks.com/reputation/?r=1&ip=188.8.131.52
We do apologize for the inconvenience and will post updates here as we have them.
Update 11:22am – It seems that Barracuda Networks is having some issues. This may be the reason for the apparent blacklisting. Their website and reporting tools are almost unresponsive and their monitoring service is unreachable completely.
Update 11:40am – We’ve been able to submit a removal request and are awaiting the results of that. In addition, we believe we’ve tracked the cause of the listing. Surprisingly, the source sends very little spam, which is probably why only one blacklist has listed us. We’ve blocked the possible source and are continuing to look for any other issues.
Update 1:15pm – We’ve confirmed removal of our servers from Baracuda’s blacklist. However, some ISPs and spam appliances will take some time to update their local lists. In our tests, some email is still being rejected, but we expect this to clear over the next few hours.