Weird problem sending email - SMTP server IP address reversed?!

[#1]

Hi
I often have problems sending email via relay.plus.net - it returns this message:
"The mail server sent an incorrect greeting: cannot connect to SMTP server 107.8.159.212, connect error 10060"
If I check the IP for relay.plus.net (using traceroute), it should be 212.159.8.107! No wonder the email isn't sending!
Weird thing - if I reboot my PC and try again it usually works ok for a while.
Have tried different email clients (Outlook, Thunderbird). For the moment, I've set outgoing SMTP server to 212.159.8.107.
Any ideas why this IP address gets garbled?
Many thanks!

[#2]

Are you actually connected to the PlusNet network when you get that error. I.e using a PlusNet broadband link ?
If you are connected via another network e.g Public Wifi or Mobile broadband then they may block SMTP access to anything other than their own SMTP relay.
EDIT: the reversed IP is a red herring , probably a fault in the way the mail client reports the error
EDIT again: Ok just ignore the first bit above :(,
I read your post again. Looks possibly like some form of DNS issue OR maybe an AV or Firewall getting in the way sometimes.

[#3]

Hi
Yes I'm using a Plusnet broadband connection. I did speak to Plusnet support but they just suggested trying a different email client. As you say, this looks more like a DNS glitch.
I am using Zonealarm and Avast anti virus, but have tried disabling both of those and still get the problem.
Forcing my email client to use 212.159.8.107 instead of relay.plus.net seems to be the answer for me, but it's still a weird one! All other web surfing etc works fine all the time.

[#4]

Hi it sounds like you may need to flush out your DNS cache
at the comand prompt type "ipconfig/flushdns" and press enter
it it happens with one particular email client and not with with another then a program like CCleaner can fix up windows registry which over time becomes bloated and can cause programs on your machine to strangely.