Mal did speak thusly:
>Thank you very much for your reply.
> > What MTA are you using?
>Postfix latest version.
>Checking the logs that you suggested, I found the cause for this
>delay, however, do not know how to get around it...
>When I am sending mails to the list from any other smtp server than my
>isp's (from webmail etc), the delivery is instant!
>However, when I send a mail from my isp's smtp server (which is the
>same smtp that postfix is using to send all mails that are posted to
>my list), then delivery takes about 1 hour!!
>Does anyone know why that could be? Is it confusing my isp's smtp server???
>Thank you for your help.
---------------- End original message. ---------------------
Sounds like they have implemented greylisting as an anti-spam measure
and have set the retry period to an hour.
Do you see anything in your MTA logs that looks something like this?
reject=451 4.7.1 Greylisting in action, please come back in 00:10:00
If so, you need to get with their sysadmin and have them whitelist
your mailman server.
Venimus, Saltavimus, Bibimus (et naribus canium capti sumus)