Use of default mailbox

[#1]

When I joined PN I was allocated the following email addresses allocated  (johnsmith is just to avoid using my real name):-
johnsmith@johnsmith.plusnet.com
john@johnsmith.plusnet.com
I found setting up my android phone (stock jelly bean email app)  that is was impossible to setup email for john@johnsmith.plusnet.com - the settings would not authenticate. I was using johnsmith+john@johnsmith.plusnet.com for POP username and just john@johnsmith.plusnet.com for SMTP username.
If I use johnsmith@johnsmith.plusnet.com for POP username and just johnsmith.plusnet.com for SMTP username, everything authenticates but I end up sending as johnsmith@johnsmith.plusnet.com instead of john@johnsmith.plusnet.com mail.
I created a new email mailbox for my wife:- wife@johnsmith.plusnet.com. I can setup android email perfectly fine using johnsmith+wife@johnsmith.plusnet.com for POP username and just wife@johnsmith.plusnet.com for SMTP username. Emails send and receive correctly using the wife mailbox.
BUT it will not work in the same manner for john@johnsmith.plusnet.com which is the default in the PN settings.
So I created a new mailbox me@johnsmith.plusnet.com and made this the default.
Now I can correctly configure email for the john mailbox ie johnsmith+john@johnsmith.plusnet.com for POP username and just john@johnsmith.plusnet.com for SMTP username.
So something about being the default mailbox is preventing the email setup. working.
So great everything is working except now I want to use the MyMail App in android. This wants a single username and password and I cant get this to work.
I have tried both johnsmith+john@johnsmith.plusnet.com and john@johnsmith.plusnet.com but neither authenticate. Of course the johnsmith@johnsmith.plusnet.com does authenticate but its not the email address I want to use.
Since PN use different username for POP and SMTP because of the "+mailbox" this is probably causing the problem.
Is anyone using MyMail with a PN mailbox ?

[#2]

The username for the default mailbox is the same as that you use to log into the Plusnet website. You do not need to use the username+mailbox convention like you would with additional mailboxes.

[#3]

I've tried out MyMail (iOS) with PlusNet (Free-Online) IMAP email account. Receiving messages worked fine but I never checked if sending worked or not, as I was just curious as to their claim of secure email and I was just seeing what they were doing.
Mind you, I tested it on a standard mailbox rather than one marked as default, which you appear to be having problems with.
Oh, just remembered that I used my own domain (PN hosted) when setting up MyMail. Not sure if that makes any difference with how it handles the setup.

[#4]

@RPMosley - thats a different MyMail.
@Bob - I am trying to use a mailbox not the default account
The point I was trying to make is that with plusnet you logon on to its POP and SMTP servers using the "accountname+mailbox" login BUT the actual email address used is just "mailbox@accountname.plus.com".
When trying to setup MyMail Android App, neither of the above options will configure correctly because MyMail assumes that the email and login are the same which in this case is not true.

[#5]

I know it's not the same app as Android but it is similar. There was certainly no option to have separate usernames for the mail server setup.

[#6]

Just re-read your original post.

Quote from: jezz

Is anyone using MyMail with a PN mailbox ?

Are you referring to this?

Quote from: jezz

Since PN use different username for POP and SMTP because of the "+mailbox" this is probably causing the problem.

In most cases, you should be able to use a mailbox username for outbound authentication too.

Quote from: jezz

The point I was trying to make is that with plusnet you logon on to its POP and SMTP servers using the "accountname+mailbox" login BUT the actual email address used is just "mailbox@accountname.plus.com". When trying to setup MyMail Android App, neither of the above options will configure correctly because MyMail assumes that the email and login are the same which in this case is not true.

Still not sure I understand
e.g. I have an additional mailbox called 'mail'. The username for POP3/IMAP access is bobpullen+mail. I have just configured MyMail to use this account as follows:

I can both send and receive from this account without any problems at all. When sending, the email is sent from the address mail@bobpullen.plus.com as you would expect.
Whilst there isn't an option to explicitly specify the POP3/IMAP/SMTP login credentials, it looks to me like some translation is happening behind the background that makes it all work anyway.