Hi I have a Postfix mail server in a Debian Linux network and used to be able to connect to it on port 25 via telnet. I also have working DNS on the server. I added this MX record to the DNS zone file: Code: @ IN MX 10 server.c4.sysinst.ida.liu.se. It worked fine after that also but then I added this SPF record, the goal is that only the server is supposed to be able to send mail from the nework: Code: @ IN TXT "v=spf1 mx ip4:188.8.131.52 mx:server.c4.sysinst.ida.liu.se ~all" But after I added that I'm not able to connect using telnet localhost 25 on the server. Help would be appreciated.