On Wednesday, March 24, 2004 7:04 AM
Joseph Saracino
I've shifted our system to use sendmail (instead of SMTP) as a workaround, and we seem to be running smoothly again. I'm still curious why the system was able to send some email addresses and not others and would appreciate any ideas the community might have to debug it further.
The most common cause for this behaviour is the receiving MTA refusing the connection from your IP. Most probably you're listed on one/some black lists. Check this, if it were not only the DUL, the Dial-Up List. DUL contains netblocks known to be used by ISPs for their Dial-Up Clients. For example, if your internet connection is a DSL, you won't be able to send mail to aol.com and t-online.de at least. They simply do not want you to send their customers mails, because the originating MTA sits on a host listed in DUL. To overcome this and similar problems, the only way is to use a relay host, aka smarthost. This is usually your ISP's SMTP server. You may well book a service on any smarthost that offers it, but check first if they are clean, ie. not listed anywhere. T-Online.de offers its customers a smarthost service which seems to be clean. Probably your sendmail configuration uses such a smarthost in the end. hth, Robert Kehl -- ((otrs.de)) :: OTRS GmbH :: Norsk-Data-Str. 1 :: 61352 Bad Homburg http://www.otrs.de/ :: Tel. +49 (0)6172 4832388