Cant send mail to one domain

[defsoul]

Hi,
Im unable to send mail to this 1 domain. Everything was working fine then i keep getting this message. Any idea why i might be getting it

16EDD10581A8 51070 Fri Jul 1 12:01:43 abc@xxxxx.com
(delivery temporarily suspended: connect to mail.xxxxx.com[xx.xx.xx.xx]:25: Connection timed out)
abc@xxxxx.com

[falko]

Please check if your server is blacklisted: http://mxtoolbox.com/blacklists.aspx

[defsoul]

I already checked and it's not blacklisted. We send a lot of emails to that domain. Is there a limited number of emails you can send? I setup the debian squeeze with ispconcig

[falko]

Maybe the admin of the remote mail server uses an individual blacklist where your server is listed. I'd try to contact the admin of that mail server.

[defsoul]

I was thinking the same but they say they didnt blacklist my server, I don't seem to believe them because im able to send to other domains.It seems to be working now, im also thinking that maybe theres a limit they can recieve from a particuler bomain