Outgoing E-mail on Android Device

[#1]

Morning,
I know there are a few threads on this topic but I have found bothing that helps resolve the issue I have.
Using my phone (HTC One S) I am able to get e-mail without any problems but I cannot send them.
My settings are...
Username: My plusnet username (not e-mail address)
Password: The correct password, I've checked more times than I care to remember
SMTP Server: relay.plus.net
Security: None
Port: 25 ( I have also tried 587)
When I then try to proceed I get a warning "Authentication failed. Please verify username and/or password."
The username and passwrod are correct and are the same as the incoming settings which works fine.
I have also tried it without needing a login to send mail and although I can then complete the setup sending mail fails with the message that it is simply "unable to send mail".
Thanks in advance for any suggestions.

[#2]

Those settings seem OK. It's worth knowing what mobile provider you're using though as some will intercept your outbound mail which can cause problems when using SMTP authentication with our servers, 3 are renown for this.
I've tested SMTP auth on your account and it definitely works:

220 avasout06 smtp relay.plus.net
ehlo relay
250-avasout06 hello [84.93.221.17], pleased to meet you
250-HELP
250-AUTH LOGIN PLAIN
250-SIZE 104857600
250-PIPELINING
250-8BITMIME
250 OK
auth login
334 VXNlcm5hbWU6
********
334 UGFzc3dvcmQ6
********
235 ... authentication succeeded

Quote from: Starks

I have also tried it without needing a login to send mail and although I can then complete the setup sending mail fails with the message that it is simply "unable to send mail".

That should work if you're connected to your Plusnet connection over wi-fi. It won't work if you're not on the Plusnet network.

[#3]

Thanks for the reply Bob.
Seems like it is probably the phone network provider.

[#4]

Quote from: Bob

It's worth knowing what mobile provider you're using though as some will intercept your outbound mail which can cause problems when using SMTP authentication

I would go so far as to say that most ISPs, mobile or otherwise, intercept outbound mail sent on port 25.  I cannot remember if Plusnet offer an alternative SMTP port. 

[#5]

They do, its 587.