iPhone and iPad says IMAP server is not responding after password change, but works on other devices I’m having a bit of a brain-scratcher with my parents’ phones and iPads. My stepmum received a notification that a attempt by someone to log in to her Google account (with the right password) had been blocked, so I started changing passwords for the accounts variations of that password were used.
One of those accounts is an IMAP e-mail account associated with their website. The mail server is a simple, bog-standard IMAP server run by the host – no hosted Gmail or anything like that, just plain IMAP. Note: The problems described here also apply to the outgoing SMTP server, which is on the same domain as the IMAP server.
The e-mail account had been working on her iPhone and iPad for years – but when I changed the password in the website admin panel and then updated it in Settings → Accounts on the two iDevices, they both said “The mail server imap.server.com is not responding. Verify that you have entered the correct account info in Mail settings”, and I haven’t been able to get it to work since. All settings and credentials (username/password) have been confirmed in the host’s admin panel and are correct. The error is never “Incorrect username or password”, always that the server does not respond.
Three points that boggle my mind:

I’ve tried completely removing the account, restarting the device and adding it as a new account; it then says “Cannot connect to server using SSL” when setting up the account. Saying yes to its suggestion of trying without SSL doesn’t help; still can’t connect.

Setting up the same account (with completely identical settings and credentials, all verified to be correct in the host’s admin panel) works fine on my and my dad’s iPhone and iPad, even accessing the Internet on the same network as the devices where it doesn’t work.

The host has previously been of the format server1234.servercluster.com, with the subdomain corresponding to which actual server the website is hosted on in the host’s server park (i.e., if they move the site to a different server, you’ll have to change your e-mail and FTP hostnames too). Recently, they’ve added aliases of the format m123456.servercluster.com, where the subdomain is an unchanging identifier that remains the same across server transfers. Both hostnames work just fine on me and my dad’s devices; neither works on my stepmum’s.


As far as empiric evidence goes, then, it seems that changing the password breaks the account – even after deleting it completely – if the account has previously been installed on the device, but the same account can be added to a new device with no problems.
I spoke to the host, who were as baffled as I am. Their only suggestion was that perhaps there was a cached SSL certificate that was screwing things up, which does sound like it’s along the right lines, but I don’t see how it can be right, given that the server’s SSL certificate hasn’t changed: it’s the same as it was a few days ago when it worked fine, before the password change.
What might be causing this? Something cached somewhere on the device (and if so, how do I get rid of it)?
A last option would be to completely reset the device, but I’d really like to avoid doing that as it would take me ages to get everything back the way it was.
So I never figured out what exactly the problem was here, but the culprit must have been some sort of cached something on the devices.
A few days ago, I once again edited the accounts on the devices – and lo and behold, suddenly it worked on both the iPad and the iPhone.
So whatever it was that was cached (?), it must have been flushed (?) after a certain amount of time had passed, and then things worked as usual. All it needed was a bit of time.