topic Re: Mailstore home can no longer connect mail.plus.net POP3 in Email

Mailstore home can no longer connect mail.plus.net POP3

Markles — Tue, 28 Oct 2025 13:39:28 GMT

I've been using Mailstore Home to archive my mailboxes / delete old emails from plus.net's servers. Since the end of August I've not been able to complete a backup. Mailstore Home reports that mail.plus.net is replying with "internal server error" (I've tried POP3, POP3-TLS and POP3-SSL and none work, all have the same error).

I've tried a clean install of a version of Mailstore Home from September 24 on a different PC and that has the same issue

Re: Mailstore home can no longer connect mail.plus.net POP3

Townman — Tue, 28 Oct 2025 15:20:56 GMT

Knowing the following will help provide appropriate assistance...

Email brand
Clarification of Mail store Home operating mode - IMAP or POP3
Credentials being used - email address or account name

I know nothing of Mailstore Home beyond that which I have just read. I note tough it can work in either POP3 mode or IMAP. If the mailbox you are using is being used as IMAP elsewhere (the more sensible approach) the you should also operate Mailstore Home in IMAP mode.

Wil IMAP your sent items are stored on the server. With POP3 they are stored on the device which sends them.

A POP3 client (which is how Mailstore Home will behave with that configuration) only connects to the inbox folder- no others.

Re: Mailstore home can no longer connect mail.plus.net POP3

Markles — Tue, 28 Oct 2025 17:08:09 GMT

This is a plus.net account.

Mailstore Home is in POP3 mode for my plus.net accounts (You're allowed to configured a maximum of 3 IMAP accounts and 3 POP3 accounts and I'm using the IMAP accounts to backup another provider).

The credentials are exactly the same as are used and work in Webmail and Thunderbird (and K-9 Mail on my phone).

I know the limitations of POP3 (I've worked in IT for 40 years) and given the limits on the maximum combined mailbox size I've always managed my email storage outside of plus.net and backed up accordingly.

Re: Mailstore home can no longer connect mail.plus.net POP3

Townman — Tue, 28 Oct 2025 17:34:57 GMT

One never knows the skill sets of posters ... it is a dilemma between teaching to suck eggs and being accused spieling jargon!

I've seen some recent gremlins on some of the migrations, but Plus.com is still in the same place, though POP3 and IMAP are going via the Greenby proxy servers. My diagnostic test accounts are working fine, using the cURL commands generated by the connection diagnostic tool (link below).

You might want to give that a try to double check your credentials.

--------------------

As I wrote this, I am reminded that there is one issue I have not yet gotten to the bottom of with the business: there have been a few reports with the diagnostic tool throwing a fit with the certificate revocation checks. Empirical evidence smoking gun suggests some odd interaction with Norton and / or AVG AV tools. Something I have not bottomed out (I do not use either) and seems to be something to do with the windows HTTP proxy.

See Certificate status could not be determined error - Exchange | Microsoft Learn and https://community.norton.com/t/windows-local-certificate-revocation-block/377195/5 As I understand it, this only impacts services using the certificate outside of certain environments, therefore it does not impact the normal email clients.

This is way over my head (in spite of 35+ years in IT) and only seems to have been manifest recently.

Running the diagnostic will plainly indicate if you are encountering this hidden "characteristic". If you are then use port 143 with no encryption.

Re: Mailstore home can no longer connect mail.plus.net POP3

Markles — Tue, 28 Oct 2025 18:03:23 GMT

I've just run wireshark up:

+OK POP3 ready <1756640388.1761673760@mail.enmail.co>

CAPA

+OK Capability list follows

TOP

USER

UIDL

SASL PLAIN LOGIN

STLS

APOP doman+user Md5hashMd5hashMd5hashMd5hashMd5hash

-ERR internal server error

QUIT

Looks like Mailstore Home is using APOP even though it's not listed in the capabilities!! (I wonder if this is an issue with the proxy and was supported by plus.net originally)

Re: Mailstore home can no longer connect mail.plus.net POP3

Markles — Tue, 28 Oct 2025 18:08:44 GMT

And I can't see what's happening in TLS / SSL connections

Re: Mailstore home can no longer connect mail.plus.net POP3

Townman — Tue, 28 Oct 2025 18:15:01 GMT

Here is the old Plusnet server offering...

* Established connection to mail.plus.net (212.159.9.81 port 995) from 192.168.1.34 port 53037 < +OK Hello there. > CAPA < +OK Here's what I can do: < TOP < USER < LOGIN-DELAY 10 < PIPELINING < UIDL < IMPLEMENTATION Courier Mail Server

What is APOP? - Email glossary

Can you please run the cURL diagnostics as a point of reference.

Re: Mailstore home can no longer connect mail.plus.net POP3

Markles — Tue, 28 Oct 2025 18:14:32 GMT

With SSL and AGV enabled:

The SSL/TLS certificate verification failed. In order to skip the certificate verification, please enable the "Accept all certificates" option. Details: Unable to perform revocation check of the server certificate.

With SSL and AGV disabled:

Authentication failed. Check user name and password. The server returned: internal server error

With SSL and AGV enabled and Accept All Certs enabled: (this is how I've been running it since I installed it)

Authentication failed. Check user name and password. The server returned: internal server error

Re: Mailstore home can no longer connect mail.plus.net POP3

Townman — Tue, 28 Oct 2025 18:20:57 GMT

Interesting that you affirm that AVG is part of your scenario.

A reference point failure with the cURL diagnostics as presented and again dropping the "s" in pop3s:// will affirm that this is the same space ...

I will then try again to get a focus on the issue. It is helpful to identify 'another environment' email application issue. I suspect that a failure to replication this with 'standard' clients outside of the cURL diagnostics has lowered the perceived severity.

@dave

Re: Mailstore home can no longer connect mail.plus.net POP3

Markles — Tue, 28 Oct 2025 18:30:12 GMT

may be being "blind" but I can't see the link to the diagnostic tool

Re: Mailstore home can no longer connect mail.plus.net POP3

Markles — Tue, 28 Oct 2025 18:32:00 GMT

Looks like AVG generates it's own man in the middle certificate and that MailStore Home doesn't know about it - that would be why I've always has to run it with accept all enabled

Re: Mailstore home can no longer connect mail.plus.net POP3

jab1 — Tue, 28 Oct 2025 18:32:26 GMT

@Markles Right-hand end of @Townman 's signature block.

Re: Mailstore home can no longer connect mail.plus.net POP3

Townman — Tue, 28 Oct 2025 18:37:02 GMT

@Markles wrote:

may be being "blind" but I can't see the link to the diagnostic tool

Sorry … i forgot to point to it … i know it’s always there!!

Thank you for the explanation of what AVG is doing … but if it does that, why has it only have become an issue following the mail proxy server changes?

Rhetorical question!!

Re: Mailstore home can no longer connect mail.plus.net POP3

Markles — Tue, 28 Oct 2025 21:41:48 GMT

Basically as far as I can tell with Mailstore set to accept all certificates I get the same error as disabling AVG which is " The server returned: internal server error". Without server traces (given that I have also tried a copy of Mailstore from September 2024 that was working at that time) my guess is that something about the new server doesn't like the way Mailstore works.

Thunderbird correctly recognises the AVG POP3 proxy.

Re: Mailstore home can no longer connect mail.plus.net POP3

Markles — Tue, 28 Oct 2025 21:47:41 GMT

Googling "Courier Mail Server" (the old implementation) it's docs say that it supported APOP (transmits md5 hashes of passwords rather than passwords)

Re: Mailstore home can no longer connect mail.plus.net POP3

Townman — Tue, 28 Oct 2025 22:24:53 GMT

As a diagnostic test, can you try using the IP address in post #7 in place of the mail.plus.net server name.

Re: Mailstore home can no longer connect mail.plus.net POP3

Markles — Tue, 28 Oct 2025 23:08:22 GMT

That works perfectly - guessing that's only a short term fix though

Re: Mailstore home can no longer connect mail.plus.net POP3

Markles — Tue, 28 Oct 2025 23:13:37 GMT

And not surprisingly "accept all certificates" needs to be enabled even with AVG disabled

Re: Mailstore home can no longer connect mail.plus.net POP3

Townman — Tue, 28 Oct 2025 23:21:53 GMT

No, it most certainly is not a fix. It’s a diagnostic comparison.

@dave / @plusnettony

This hints at a subtle difference between the old and the new POP3 proxy server. I recall in the early days of the program we found something similar to do with MD5 support. Could there be another subtle difference giving rise to this experience?

Re: Mailstore home can no longer connect mail.plus.net POP3

Markles — Tue, 28 Oct 2025 23:59:27 GMT

This may be useful for AVG users:
Go to the AVG client's Menu > Settings. Search for "geek:area"

You can disable AVG's man in the middle SSL