Mail can't verify the identity of the server 'imap.plus.net"

[#1]

Hi Tina

On Monday, you wrote:

'We have been made aware of an issue whereby users are being presented with an error that states "Mail can't verify the identity of the server mail.plus.com. This is currently under investigation ...'.

Do you have any updates to this very frustrating problem that is affecting a range of users - not just me on my ANCIENT iMac desktop?

Thanks

[#2]

@perplexed1 Thank you for reaching out to us and I'm sorry to hear you are still experiencing an issue.

Yes a fix was provided earlier on in this thread by @j123, here's the details if you have not seen it:

"Looks like there is a missing Root G5 certificate on older macOS systems.

I downloaded the DigiCert TLS RSA4096 Root G5 certificate from Digicert's website. https://knowledge.digicert.com/general-information/digicert-trusted-root-authority-certificates#g5ro...

I imported it into Keychain Access and changed the trust to 'Always Trust'. Quit and relaunched Mail.app, and now all is working."

Several users have used this fix and reported it to be working, please let us know how you get on

[#3]

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@Tina11192 wrote:

@perplexed1 Thank you for reaching out to us and I'm sorry to hear you are still experiencing an issue.

Yes a fix was provided earlier on in this thread by @j123, here's the details if you have not seen it:

---

So the PlusNet response is either:

1. Install the G5 root CA on your device, if a) it's possible, and b) you have the skills; or
2. Get a new device; or
3. Get a new ISP

No mention of PlusNet fixing their certificate chain...

[#4]

Can you post the OS version installed please?

Also what is displayed under...

• Settings
• General
• About
• Certificate Trust Settings (at the very bottom)
  • Trust Store Version (should be 2025031200 for the current version of iOS18)
  • Trust Asset Version (1006)

[#5]

Thanks Tina

I have found a workaround by switching from POP to IMAP and all my missing emails have arrived.  I have disabled the pop account, but NOT deleted it.  However, should I still download the Digicert certificate and revert to POP?

[#6]

@perplexed1 

That is probably not the fix you think it is.  What port is your IMAP configuration using?  If it is 143, then that is not encrypted so is not using the new very secure server certificate.

[#7]

---

@Myhom wrote:
Yes it’s a current iPad with latest iOS installed

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@Myhom 

Post #124 was intended for you, but I got interrupted!

Being on the latest available iOS for a given device and being on the latest version of iOS are not necessarily the same thing.  Please see the ask in post #124.

[#8]

I've moved to Thunderbird, still using the PlusNet addresses. Seems to work so far.

[#9]

Using encrypted connections on ports 993 / 995?

[#10]

According to the plusnet email set up information, IMAP's incoming port is 993 and the outgoing, 587.  When I added the IMAP address in Mail using the information it wanted, it automatically connected.

I can't use 'the new very secure server certificate' since I am on 10.13.6 (iMac aluminium desktop, mid 2011) with no, or very little option to update, and certainly not to whatever is the latest OS.  The latest certificate I have is G4 root - means nothing to me at all - and it is has not expired.

[#11]

All very confusing. I have re enabled my SSL on the incoming settings in my  email accounts and received message pop up with an option to continue which I did and now the emails are getting through without any server certificate error. Working on iPhone 8 (16.7.11) and IPad 5th Gen (16.7.11).

Not sure yet if this is temporary or lasting.

[#12]

@arm_900Q 

You have (effectively) accepted the certificate without verification … on the basis of you know where it comes from.  Having opted to trust it, you should not get prompted again.

[#13]

Both Bluemail and Thunderbird apps work on an old android 8.1.0 tablet, but personally I prefer Thunderbird. The calendar integration on Bluemail was poor and unnecessary.

Also had to add G5 certificate to partner's 2 old ipads, but found earlier instructions from j123 slightly confusing as I don't use Apple kit myself. (Finally found Certificate Trust Settings in General -> About section which allowed me to always trust the new G5 certificate).

[#14]

My iPad is at iOS 17.7.9
Trusted cert 2024040500 version 1006 expires 2026
Two days ago this was a trusted cert now it’s not?
Receiving same message for pop mail server now also.

[#15]

Can you update it to 18.xx - if so, you may find the trust cert will update to the current version?