Inbox folder just keeps growing

I have folder size set to 100 but there are currently 1435 messages when I do select-all, and there’s a noticeable delay when I launch K9 while inbox is loaded. I also can’t find the old commands to clear local messages (without deleting), which I used to do if I’d loaded more and more and more, to get to an older one for example.

While I’m asking, is there any way to mark a read message as unread?


The way I clear a mailbox of messages greater than my default size is to change the “local folder size” to some other value, refresh the folder, then change the folder size value back to what I want and refresh the folder again. That approach works in both 5.6 and the 5.7 beta releases.

1 Like

Thank you. I tried changing to 250 but don’t see how to refresh the folder. I did do a check for new mail, but the folder still has >1400 emails.

After changing the value go back to the inbox and do a refresh by pulling down the message list display. Then, go back and set the value (back to) the smaller amount, then again return to the inbox and refresh it, again.

Thanks, that’s what I thought you meant. I did that (changed 100 to 250, checked mail, changed 250 to 100, checked mail, still 1566 when I select-all). Not sure what else to try. [added: this is a POP3 account, not sure if yours is]

Ah, I wouldn’t expect this to work with a POP3 account, and suspect that this option is an artifact of the IMAP focus of this app.

With POP, the base design assumption is that messages are pulled to the client and (often by default) then deleted from the server. Allowing for easy clearing of the client’s message cache could result in non-recoverable message loss. One client instance that doesn’t delete messages from the server can’t assume that the user doesn’t have another client instance that does deletes, so message cache clearing needs to be something that the user controls (carefully) based on their knowledge of their client settings.

Sorry but I confirm the above problem: at the moment in K-9 Mail app I have a unique POP3 account which local folder size is set to 2500 messages, but at the moment I have approx 3900 local mails in this folder, the folder is growing and growing without auto-cleaning. Changing local folder size to different values and than refreshing doesn’t change anything.

The account settings are to not delete server messages, because on POP server all deleting stuff is done from other desktop mail client (Thunderbird).

In previous old stable versions up to 5.600 , same settings, the local folder size worked as expected, since upgrade to 5.8xx inbox folder started to grow.

Any suggestions?


1 Like

I don’t want to sound flippant, but does your ISP also offer IMAP access to your mail account? If so, then I suggest that.

Reason: with POP when you access the mailbox, ALL messages are (re)moved from the server to the client; whereas with IMAP all the messages remain on the server, and some of them are copied to the client.

Therefore, also, POP is no use if you have multiple clients accessing the same account; because messages will be (re)moved to whichever client accessed the inbox first after the messages had arrived.

1 Like

That’s not how my email works with my ISP. I have The Bat! on Windows, emails only leave the server when I empty trash folder (in TB!) or when I go in and delete using webmail. There’s a setting in TB! to specify whether to delete on download.

Maybe TB! isn’t conforming to POP3 standard, but I can download messages on Windows then download in K9 (I think they are marked Read though).

Pretty clearly AlexDF has the same functionality, so I don’t think it’s accurate to say that’s not how POP works for them.


Agreed. The hints that POP might’ve removed are very concerning. The great thing about POP access - as others have posted here - is that we can view our emails on our cell phone and delete, without changing their underlying status on the server. When I get back to my desktop I can view all of my emails in a normal way, but also see what’s going on while on the go with my cell phone. Please do not remove pop access from future additions of K9.


I confirm the scenario : k9 pop3 access only to rapid check email, main mail access on desktop TB which manages deleting old messages on pop3 server after a couple of days. In this scenario the server space occupation is very low, of course there are pros and cons, but it was correctly functional up to 5.600, now since 5.8xx k9 local cache deletion is broken. What’s changed in this new main version?


I have used POP for decades, and just because an email is read ( downloaded by third party software ) does not mean that it will automatically get deleted from the server. I, too, have a problem with the current version retaining more emails than the local folder size limit. It was working in previous versions.

1 Like

What worries me is that the developers won’t care how people use it (as with top-menu), and will either remove POP3 support or further break it just because it’s how they think we should use it.

I’ve been using Yahoo! Mail and Gmail apps for their respective services, and I have to admit I don’t hate the former. Not sure how well (or if) it handles POP3 though.

1 Like

Utter bulll!! If you set the pop client to ‘do not delete messages on the server’, it doesn’t. I have my mobile set to ‘do not delete messages when they are deleted on the server’, because certain messages I keep for longer.
I have a desktop client that fetches every mail box once per 10 days, and deletes the messages from the isp servers, both pop and IMAP. Then, I periodically search mobile inbox for spam strings, select all, and delete.
Unless you set the client to ‘delete messages when deleted on server’, they’re going to remain. It doesn’t matter whether you resize the folder.That doesn’t tell K 9 to delete anything! And even ‘delete’ only puts it in the trash. So, you have to clear that out from time to time.
I let my main mobile inbox fill up to maybe 4-5000 messages, and search for spam keywords, such as ‘warning’, ‘love’, ‘girlfriend’, ‘drugs’, ‘free’, ‘car’, ‘vacation’, ‘discount’, ‘congress’, ‘conservative’, ‘liberal’, ‘lust’, ‘pharmacy’, and nuisance domains.
I usually get 3000 messages gone in 5 minutes, by getting search hits, and manually deleting them all. If I delete something good, it’s always going to be on the desktop, because that is the only device set to delete messages off the isp’s mail servers. I look through once a week, just
to be sure. And that client saves everything until I manually remove it.
So, I never need to worry about losing anything.
The email client on the PC is backed up with everything else, so if the drive in the PC fails, it doesn’t matter.
I never use the cloud! They say, if you lose the key, password, or whatever else; not even the cloud service can retrieve your files. They mean they won’t retrieve files for clients who have lost access. Otherwise, they’d be vulnerable to government searches, and rubber-hose cryptanalysis (not pretty). But if they make clear to everyone that they cannot retrieve files if the client loses access, they can tell governments and criminals, we don’t have the capability!
Well, where did the key come from? Did you make it yourself? No the cloud service gave it to you. How difficult is it to retain copies of cryptographic keys? Access goes to well-heeled, and law enforcement who are willing to pay, big time.
When law enforcement claimed they couldn’t access an Apple phone owned by a mass shooter, that they needed help from Apple, there was forensic software available to instantaneously crack the security on that phone, for 1400.00USD. They just want to lull the public into a sense of security that law enforcement can’t get into their mobile devices, which makes people more lax in security, which doubles the effect. Don’t use cloud backup or applications! It’s cheap up front, but it will be expensive in the end! It’s only private if you have control over physical access to the hardware, and you make the encryption keys yourself!
Sorry for my long post, but I like to hide tidbits randomly, here and there.

1 Like

I would kindly suggest that the way to get your problem solved, is not in insulting and swearing at other unpaid volunteers trying to help.
POP was designed to work in the way he said, and clients have found ways around that to emulate an IMAPish behaviour.

That having said, POP as a protocol is way more obsolete than IMAP, and developer resources stretched thin, I would not be surprised if it were dropped. You have a first hand example of behavioural differences and Post Office Protocol - Wikipedia has more in the comparison to IMAP section.


The second paragraph of the Wikipedia article you linked begins with this:

POP3 clients also have an option to leave mail on the server after download.

and this is the 2nd bullet point in the “comparison to IMAP section” you highlighted

POP moves the message from the email server to the local computer, although there is usually an option to leave the messages on the email server as well

Here’s a screen capture of The Bat!'s mail management options. 09.01.2021-01.45.00

1 Like

I wonder if the “bull” is considered swearing on this board. I wasn’t aware development was done by a convent of consecrated religious sisters!
But to tell other members there’s no way to prevent deletion of the messages on the POP server brings us back to the stone age!
Why take something useful out of the program, when it’s never going change? You can just leave the POP code in. You don’t need to change it or maintain it! SHEESH! I would think the developers would save much more time avoiding the onslaught of enraged users who probably chose K 9 simply because it works well with POP.
If not for that, many other clients work better.
And a significant number of email servers are POP compatible by default, which makes it kind of universal! At least I could always get POP to work in a pinch.
It’s like Linux just dropping development of core-tools!

1 Like

Could we just tamp down the energy here? It’s indisputable that POP3 is still a widely used email protocol by many K9 users, and many also have their settings to leave email on the server for retrieval from other clients, while using K9 on their mobile device to read those emails on the go. Let’s just leave it at that, as a serious, not rare example, with the request that POP3 functionality be left in this app. Thank you all.


Apparently yes, as bugs do POP up (pun intended) as this thread demonstrates aptly…

1 Like

I guess it depends on how well the various objects, or classes, are isolated from others. I don’t do Android development. Sorry if my ignorance shows.