% telnet mfsmax.docomo.ne.jp 25
Trying 203.138.181.112...
telnet: connect to address 203.138.181.112: Connection refused
Trying 203.138.181.240...
telnet: connect to address 203.138.181.240: Connection refused
Trying 203.138.180.112...
telnet: connect to address 203.138.180.112: Connection refused
Trying 203.138.180.240...
telnet: connect to address 203.138.180.240: Connection refused
telnet: Unable to connect to remote host

ドコモの接続元規制データベースは頻繁に更新されるんで、
今だけの現象かもしれんがな。