iOS8 unable to send emails via PN

[#1]

incoming email is OK.
Many places I have been at outgoing email has been OK, too, but the last two create an error: "Cannot send mail. A copy has been placed in your outbox. The recipient n was rejected by the server.".
No settings have been changed and password is present & correct. Outgoing mail is fine at home.
Lots of stuff on the 'net. Known iOS fault, no answers that I can find.
Any ideas here?

[#2]

How are you connected to the Internet at the time? The problem could be due to restrictions applied to the Internet connection itself, rather than an issue with the configuration of your email application.

[#3]

Quote from: Mardler

No settings have been changed and password is present & correct. Outgoing mail is fine at home.

As Bob says it could be the connection you are using.  However just let's rule out some of the common issues in not being able to use the SMTP server when not on the PlusNet network.  Can you confirm that the outgoing server is configured as follows...
Server: relay.plus.net
Port: 587
Server requires authentication: account (or mailbox) username (username+mailboxname) and password
SSL: Off
Send password as plain text
If everything is working at home then that rather suggests that the port is set to 25 and / or authentication is not configured.

Some networks will block access "off network" on port 25.  Some networks will block any access to an external SMTP server.
HTH.

[#4]

I think it's an IOS problem. It's happened to me in the past and I don't use the PN mail servers.
I got over it by deleting the mail settings on my iPhone and re-entering them (with a reboot in between)!

[#5]

Hi off,
You are not wrong on that point.  Apple email settings seem to have a habit of getting somewhat screwed for no apparent reason.  Earlier this week one of my PN email addresses got "stuck" on my iPad - it would not RECEIVE.
If I looked at all mailboxes, it would simply report (quite promptly) "last updated yesterday at xx:yy"
Looking at individual mailboxes would receive OK, except for one which reported the above.
I deleted that account and reinstated it and all was fine, except I was left with an orphaned SMTP configuration.

Quote from: Mardler

incoming email is OK. ... Outgoing mail is fine at home.

Leads me to believe this a ports and authentication configuration issue.

Kevin