Outlook error: 550

[Paddy]

'error 550: relaying to X prohibited by administrator.'

I get that if i try to send plain text using three different accounts. Only one account seems to work. Any idea what it is?

[Paddy]

hmm.. i can send an email from an @ntlworld.com addy to another @ntlworld.com addy. But I cant send one from @ntlworld.com to anywhere else... My @bushe.co.uk addy wont send anything...

[Paddy]

it would appear that my @bushe.co.uk addy requires me to be using their dailup.

Bugger.

[Paulr]

Well yes, this is true - no ISP will allow their mail servers to be open for relaying.
You will only be able to send e-mail through a mail server when you are logged onto that ISP's dial-up connection - standard procedure that.
You can however receive e-mail from all of your accounts no matter which one you are logged into.

I simply set the outgoing mail server to the same on all my accounts - I set it to the ISP I use 99.9% of the time.

Example:

I use Virgin.net

So for my @virgin.net account I use

Incoming mail server pop.virgin.net
Outgoing mail server smtp.virgin.net

username - my virgin.net username
password - my virgin.net password

For my @prawlings.net account (personal domain)

Incoming mail server pop.prawlings.net
Outgoing mail server smtp.virgin.net

Username - my prawlings.net username
Password - my prawlings.net password

For my @swgtips.com account (personal domain)

Incoming mail server pop.swgtips.com
Outgoing mail server smtp.virgin.net

Username - my swgtips.com username
Password - my swgtips.com password

As I'm phyisically connected to one of Virgin's IP addresses I don't need to authenticate myself to send mail through their servers.

Edit:
Actually this is how I used to set my mail up, due to the way my domains are now hosted I have my own SMTP/POP servers which I use for sending even when attached to virgin.net - but I do need to authenticate by receiving mail before I can send so that my IP address is temporary added to the authorised relay list.