Problems sending Plusmail with IPad Mail

[#1]

I'm currently receiving Plusmail in iPad Mail for one of my mailboxes but I am unable to send any.  I get the error message, Cannot Send Mail: The username or password for "smtp.plus.net" is incorrect.  And yet the username (including + with the mailbox name) and password are correct and are working on other devices and with Webmail.  This is new.  I've been using iPad Mail with Plusmail over a decade.  Is anyone having similar problems or able to suggest a fix?  Thanks.

Don

[#2 · Accepted solution]

Nothing like posting to make one re-think the problem.  I've sorted it now, so need to reply!