smtp outgoing email error

[jellied]

Got a most strange issue with my HTC email.

All email - hotmail & smtp works fine for out and in when on wifi
SMTP outgoing email fails when on not on wifi.

Vodafone says there's no problem, and ISP claims there's no changes.

It's happened once every 6 months previosly but always been cured by deleting the email account on the phone.

I'm at a loss as to how to progress this.

I can't even think where to point the finger, I feel it must be the Vodafone connectin rather than any phone settings.

[Kim]

What SMTP server are you using to relay outgoing email, and are you using a username/password to authenticate?

[robgul]

My HTC Wildfire on Vodafone contract accessing BT account - using either the in-built Mail client or K9mail - this is my aide-memoire for the settings to fix the issue (on either WiFi or direct Internet mobile connection)

E-mail from phone:
Mobile = log in to send
WiFi = NO log in to send

Rob

[jellied]

smtp server is the domain hoster: smtp.hoster.co.uk
login is required
user name is XXXXXXXXXX-username
server is : smtp.xxxxhost.co.uk
security type  none
server port: 25

i really don;t understand why the connection type should matter unless when not on WiFi it goes through different path.

[Kim]

i really don;t understand why the connection type should matter unless when not on WiFi it goes through different path.

Exactly that.  On Wifi, your phone appears to be on your broadband provider's network.  On 3G, it appears on your mobile provider's.  Completely different route to the internet.

Classically, this problem occurs when a provider allows unauthenticated SMTP relaying from IP addresses within their own network, and the user connects via another provider, at which point it refuses to relay (because that's a standard way of delivering spam).  The usual fix is to use authentication, which requires the SMTP server allowing authenticated relaying from anywhere.

But it sounds like your third-party SMTP server is already doing that, so it's going to be something more subtle.

I'd start being suspicious that the provider (in this case Vodaphone) were blocking port 25 outbound.  That's not unheard of (again, as a spam-prevention measure), and is what I was ranting about AOL doing the other week.  Port 587 might be an option, but smtp.hoster.co.uk doesn't appear to be listening on it.

Or it could be a routing problem, or something.

[Feanor]

i really don;t understand why the connection type should matter unless when not on WiFi it goes through different path.

The reason it matters is anti-spam filtering.

SMTP e-mail was designed as an insecure system.
We've been living with the consequences of that for years.

So ISPs provide an outgoing SMTP server, for the use of *their* clients.
To prevent it being abused by others, it may be configured to only allow outbound mail from *their* IP address-block, ie their customers on-network.
To allow their customers to continue to send via their outbound SMTP when the customer is off-network, SMTP authentication has been devised.

So in general, most ISPs won't allow outbound SMTP via their servers if you are coming in from an IP address which is external to them.   They may allow a work-around with authentication.

ETA: And as Kim said, even when you're off-network, and your SMTP server is allowing external authenticated access, it's possible the 'external ISP' you are temporarily connecting via does not allow standard SMTP sessions out of it's network, forcing users to use the 'temporary connection ISP' SMTP relays.   Work-arounds involve your SMTP host accepting connections on an alternate port.   It's all a bit ugly.

[jellied]

Ah ha - that's a lot clearer. Obvious really I suppose. shame vodafone didn't mention this as a possible cause, fruitless afternoon turning off, taking the sim card out, wringing a chicken neck and running three times around the workshop.

Anyway, K9 mail has just been downloaded and does something that the native app doesn't.

[Kim]

On closer inspection you'll find that K9 mail does several things that the native app doesn't.   

At least two of which (IMAP IDLE and moving messages between folders) I'd consider to be basic functionality in a mail client.