can you post a screen shot?

This message was created automatically by the mail system (ecelerity). A message that you sent could not be delivered to one or more of its recipients. This is a permanent error. The following address(es) failed: >>> [email protected] (after MAIL FROM): 550 5.7.1 Unfortunately, messages from [69.168.106.50] weren't sent. Please contact your Internet service provider since part of their network is on our block list (S3150). You can also refer your provider to http://mail.live.com/mail/troubleshooting.aspx#errors. [SN1NAM01FT004.eop-nam01.prod.protection.outlook.com] ------ This is a copy of the headers of the original message. ------ Return-Path: <[email protected]> DKIM-Signature: v=1; a=rsa-sha1; d=wildblue.net; s=20170921; c=relaxed/simple; q=dns/txt; [email protected]; t=1548462727; h=From:Subject:Date:To:MIME-Version:Content-Type; bh=L+4WhpjsdWHkOntpjvw8/THgCRU=; b=jNuVS4y9Dj6oAFdFkhbcas3E+VgHyi5DbOsolpPTZHv5b1iszvTdlam0UlkohNIy PsjN+g8o6RXUvYobfhUgT6Ai0KsSkIEH+B4HP7o14avC+Q5s5j2FWCK2+QlSZxdD fNbWRCSW3QqA+fr/LijrAHcQmvKjZFIjh6cknMP+7QV+bvW36cAjZPi6Zr24mG5W IEtVZ9bCBV16biYfuy6ZZz2+SKlB22JPaBJ8TuQZtC1O9K8gWa7Zls/JjiSd0fnJ aw54mfMgVtwHy3teWkI08/31sY0mkvd9aucOaxjbYBhwxwacgmi0n9dDFJpl8Mlw ki59sQ2VeEhK/omHzBx6qQ==; X_CMAE_Category: , , X-CNFS-Analysis: v=2.2 cv=UqohDK4B c=1 sm=1 tr=0 a=N4R7/PNAKQajMtO43H0HsQ==:117 a=KGjhK52YXX0A:10 a=FKkrIqjQGGEA:10 a=KaKI7MrsauEA:10 a=IkcTkHD0fZMA:10 a=3JhidrIBZZsA:10 a=Guoj6Q1NuGQA:10 a=2uHmD35bF6MA:10 a=hmZo9IHbGtPS0ncrnEsA:9 a=QEXdDO2ut3YA:10 X-CM-Score: 0 X-Scanned-by: Cloudmark Authority Engine X-Authed-Username: aGRnYXJhZ2VAd2lsZGJsdWUubmV0 Received: from [10.80.118.19] ([10.80.118.19:56652] helo=md06.jasper.bos.sync.lan) by mail2.directv.syn-alias.com (envelope-from <[email protected]>) (ecelerity 3.6.25.56547 r(Core:3.6.25.0)) with ESMTP id B9/15-30222-78AAB4C5; Fri, 25 Jan 2019 19:32:07 -0500 Date: Fri, 25 Jan 2019 19:32:07 -0500 (EST) From: CINDY WHITTON <[email protected]> To: xxxxxxxxxxxxx<[email protected]> Message-ID: <[email protected]> Subject: Email MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit X-Originating-IP: [99.197.215.139] X-Mailer: Zimbra 8.7.6_GA_1776 (ZimbraWebClient - FF64 (Win)/8.7.6_GA_1776)Thread-Index: 1MoCLwFpM/VbSlDisosJvcmjVYJX/g== Thread-Topic: Email

Microsoft either has blocked your IP address, or a whole block of IP addresses representing your ISP, or they have blocked the mail service https://www.zimbra.com/ I can't tell exactly who is blocked. It has nothing to do with Mozilla. You could try to get around the problem by using a VPN, which will replace your personal IP address with that of the VPN server. If that fails, you will not be able to use the Zimbra mail servers. Once a mail server is blocked, it is extremely difficult to get it unblocked because there are countless independent blacklists out there. Removing the block from every blacklist is hardly possible. Can you please clarify if you are using Thunderbird or Firefox with a web-based email system?