Full iCloud Mail Inbox - iCloud password is incorrect even after updating

This issue started last week when my family storage reached 2TB out of 2TB. I stopped receiving or sending mail due to this so I opted to upgrade my iCloud storage plan to 4TB.

This should have fixed my issue but after a few days I noticed I still was not receiving mail and I tested by sending an email to a friend and it hits me with:

Cannot Send Mail

The user name or password for

"iCloud" is incorrect.

I was able to fix this (temporarily) by signing out of iCloud on my iPhone completely including disabling Find My iPhone and signing back it. My mail started working and I assumed all was good.

24 hours later - the issue started happening again. I kept checking my mail for a verification code for a software I was signing up for and nothing came so I checked the storage to make sure and it does say 2.1TB of 4TB. I upgraded to the 8TB plan to be safe with no luck. Still not getting mail. I then removed Family Sharing with storage. So now it is saying 551.6GB of 8TB for storage. STILL NO MAIL!

I then figured the storage was not the issue even though everything online says I am not getting mail due to iCloud storage being full. So I tested my mail again by sending an email to a friend and once again, I’m hit with the same “Cannot Send Mail The user name or password for

"iCloud" is incorrect. ” message as earlier.“

My next solution was to update my iCloud password. I updated my password and voila-my mail started working again. I was able to receive mail and send mail successfully… UNTIL - 24 hours later, the SAME issue occurs!! I get the same message once again when I tested sending an email and I am not receiving emails.

I believe at this point there is an issue from the iCloud servers and will call to escalate to an Apple engineer tomorrow morning.

I also noticed in settings > iCloud

it says “Set Up” next to Media & Purchases. When I tap this, a screen pops up with a colorful animated circle and my iCloud info in the middle along with “Log In”. Tapping Log In leads to an error. Not sure if this has anything to do with the issue before.

iCloud on desktop also stops working when this issue occurs.

When others send me an email, they get back the following message:

Recipient inbox full

Your message couldn't be delivered to ************@me.com. Their inbox is full, or it's getting too much mail right now.

So far the only temporary solutions are:

1. Sign out of iCloud completely and sign back in.
2. Change your iCloud password in Settings > Your Name > Sign In & Security > Change Password

These solutions work temporarily for 24 hours before the issue occurs again.

Does anyone else have this issue?

TLDR; unable to receive mail or send mail in iOS. plenty of iCloud and iPhone storage, payments up to date, passwords updated, signed out and back into iCloud, disabled mail and re-enabled, all work as temporary fixes but issue occurs again 24 hours later.