strange smtp blockings

[Jaume Teixi <teixi@6tems.com>]

hello,

one of my servers has problems sending mail to anothers: Connection Deferred

its not a sendmail issue because telnetting the hosts at 25 also is blocked
rblcheck doesn-t show any block for its ip
other ips on same range are not blocked on that hosts
it happens on some kind of hosts on different networks and with different mail systems
on hosts.allow i-ve sendmail: all and on hosts.deny ALL: PARANOID

I cannot understand this issue, any points?

tx!

jaume teixi.