Rick,

The reason i used top was because I noticed that mailscanner and smtpd were always on the list UNLESS the issue was occurring. I will try ps + grep next time as well. As for the ips they resolve quickly however they are all listed in /etc/hosts as we do not have an internal DNS.

-jr

replies-lists-a1z2-centos@listmail.innovate.net wrote:

using "top" to look for processes probably isn't the best approach as (by default) you'll only see the more resource intensive applications. you'll probably get a better picture of things related to a specific application using "ps" (and grep).

when you connect to an MTA (e.g., postfix/sendmail) it will try to do an reverse map lookup on the ipnumber of the inbound connection. if you don't have in-addr.apra entries for your ipnumbers, or if the machine running your MTA is having trouble getting to the dns server for the ipnumber range, then you'll get the type of delays you seem to be seeing. ultimately the dns will time out (the number of dns servers you have listed in your mail server's /etc/resolv.conf will effect this - more is not better).

you can get a sense of whether this is the issue by doing lookups (on the mail server) of the ipnumber(s) for connecting machines that are encountering the delay. depending on your configuration, your server may cache a result, so the first may be slow with subsequent ones being fast (until you hit the TTL on the record).

[by the way, when sending to a mailing list please try to suppress your confidentiality notice as it's meaningless in this context, and takes up a lot of lines.]

• Rick