Unable to Send Email using iPad and iPhone

[#1]

Hi Guys,

I have a legacy domain name hosted on Plusnet that I only use for email - yesterday I stopped being able to send emails from either my iPhone or my wife'siPad.

The error message is:

Cannot Send mail

The (email address) is not a valid email and has been rejected by the server.

I am not sure what has changed  - this began yesterday.

Any thoughts anyone?

[#2]

Webmail doesn't work either

When I try to send a message the error is;

Message not sent. Server replied:

Requested action not taken: mailbox unavailable
550 <{mailbox}@{username}.plus.com> invalid address '{mailbox}@{username}.plus.com'

[#3]

YEP - someone, somewhere, has fouled up. Have you had any updates on either of the iDevices that may have caused this?

This is becoming a major rolling issue.

[#4]

This issues is connect with the too many addressees issue reported elsewhere.

[#5]

Thanks @Townman 

I ran the email diagnostics but did not spot any errors on  three mailboxes set up on that account.

In the meanwhile I was on hold to plusnet help desk. The operator originally told me it was an iOS and Apple need to to sort it.

I fired up an old windows 10 machine with Thuderbird on it and tried to send an email; that reported an error;

"An error occurred while sending mail. the mail server responded: (email address) recipient rejected - too many recipient in the last hour...."

So not an iOS problem. They have raised a ticket for me.

[#6]

---

@Cerberos wrote:

The operator originally told me it was an iOS and Apple need to to sort it.

So not an iOS problem. They have raised a ticket for me.

---

There has been an unhealthy spate of email issues, some of which have in part been down to iOS / Apple not updating their devices to the current security standards.  It is thus easy to see how the wrong advice might have been given by the front line staff - they are not email experts!

There is also the characteristic of the individual answering ... and the time lag between individual calls.  At the point that a critical volume occurs, a new perspective is developed.  Also this issue comes and goes, depending on the time of a test.  Profiling the issue requires knowledge of how the service works.

The positive manner in which my call was handled indicated that there is the correct awareness of the issue and they are on the case.

[#7]

Moderator's note:
Thread locked in favout of https://community.plus.net/t5/Email/SMTP-error-452/m-p/2017606#M51937