The first sentence in your post states "I can not send mails from the google GMAIL domain. My mails are blocked and I receive the following notification," but, because the error message that follows is coming from a Gmail server and you listed "Zimbra" as a tag for your post, I'm wondering if your first sentence is not misworded and that it should be "to the GMAIL domain" rather than "from the GMAIL domain." I'm assuming that is the case, since the Zimbra software suite contains an email server component and I see the IP address listed by Gmail for the sending server is
184.108.40.206 and that takes me to a Zimbra page, if I access
It appears that Gmail may have placed that IP address on its block list, e.g., from How to Test If an IP Address Is on Gmail's Blacklist.
If Google's put you on the blacklist, your network's email servers
will tell you. Gmail responds to blacklisted addresses by sending the
servers either a 421 error or a 550. The 421 is for temporary
problems; 550 indicates a complete block on mail originating from your
Internet address. You may need to contact your email provider to
research the servers. You can also enter your domain name on a website
such as MX Toolbox and see if the site reports a blacklist.
You can view the MX Toolbox check for the IP address on various DNS-based Blackhole Lists (DNSBLs) at blacklist:220.127.116.11. The IP address is currently on the ZapBL list, which reports it has seen spam 4 times from that IP address since August 15, though I don't know if Google is using that list. I would suspect that Gmail isn't using that list, but has also adjudged some email from that IP address as spam due to its own checks of the content of email from that address. E.g., see the "Gmail Blacklist Criteria" section at How to Remove Your IP from the Gmail Blacklist. Try going to Google's support page at My domain is having delivery problems with Gmail troubleshooting page. Unfortunately, you probably won't be able to get the IP address removed immediately.