– Mysterious Reply-To Header in Apple Mail

I send e-mail with Apple Mail from two different accounts – lets call them A and B. Years ago I set the Reply-To header as my A account address (I think to force use of my ‘canonical’ address), since then I added my B account. Now all of my outgoing e-mail has the Reply-To header set to my A address. This causes considerable confusion to observant correspondents e-mailed through my B account. So, I’d like to fix this.

Here’s where the mystery begins. I don’t remember how I set the default Reply-To header. I would have thought that I would have used:

defaults write UserHeaders ...


defaults read UserHeaders

tells me “The domain/default pair of (, UserHeaders) does not exist.”

Next, I looked at the configuration on our e-mail provider, FastMail, to see if they might be setting a default Reply-To header. but I didn’t see anything there.

Then, I tried resetting Apple Mail back to its default state using the instructions in How to reset mail to factory settings on No dice.

And then, the method in How to Fix Mail App Not Working After macOS Update. Strike four.

Manually setting the header when I’m writing an e-mail doesn’t work. The value I set gets overwritten, by the value for account A.

Where else could the header be set? – Opening an email in Sent does not show the complete thread it belongs to in iOS Mail

I have a Fastmail account configured via IMAP in iOS Mail app,
with the Organize by Thread and Complete Threads toggles both
turned on in Mail settings.

Thanks to the latter, when I open an email from the Inbox or Archive
folder, it is shown in the context of its thread, with the preceding
and following emails also being shown above and below the opened one.
However, when I open an email from the Sent folder, the thread view
does not activate, and only that singular email is displayed.

Why is that the case? What is the reason for Sent being treated
differently from Inbox and Archive in regards to threading?
Is it possible to enable the thread view for emails opened from
Sent, as well?

From my experience, this behavior persists both on iOS 13 and 14.
(Perhaps it dates all the way back to the introduction of the thread
view in Mail?)

Listing an “On My Mac” Mailbox by Sender in Apple

I archived email from an online account of mine to an “On My Mac” mailbox in apple on Catalina Mac OS 10.15. I saved my “Sent” email to a separate “On My Mac” mailbox as the “Inbox”. The mail in my archived “Sent” mail box is not listed by sender (me) rather than the recipient. Is there any way I can get the mailbox list to show the email recipient instead of or in addition to the sender? – Gmail/Mac Mail – how can I address disk space issues?

I’m running High Sierra on a 2016 MacbookPro. My business account uses G Suite (Gmail). I use Mac Mail and sync to my business account. I have a few other email accounts but my business account is by far the biggest.

I’m running out of drive space. I currently am showing 50GB space remaining on the 1TB drive in this Mac. Mail is the biggest user of disk space, with /Library/Mail taking up 160GB of space.

I’m trying to free up space but I don’t seem to be doing a very good job of it. I have tried Erase Deleted Items, which got me a little. I created a smart mailbox for email with attachments that is older than 5 years, and am using Remove Attachments but it’s a slow process. If I try to do more than about 500 emails at a time, Mail crashes. And removing attachments from 500 emails takes quite a few minutes. I have about 30,000 emails in this smart mailbox so it’s going to take a while to go through all those, and I’m not even sure this is the best approach, because it doesn’t seem to be having much of an effect on disk space so far.

One thing I notice inside /Library/Mail/V5 are what appear to be two “accounts” (folders with letter/number names) that both are large in size. One is 81GB and the other is 72GB. Looking inside those, the smaller one appears to be “On My Mac”. It’s full of folders of filed mail (I am a filer. Everything I get that I want to keep gets filed according to client/project/etc.) The larger one contains several subfolders, the only large one of which is (Gmail).mbox, which contains All Mail.mbox.

I am pretty sure that is syncing “All Mail” from Gmail, and I think the problem is, because I am a filer, I end up with two copies of many messages: One in On My Mac and one in the Gmail Archive or All Mail folder, which is getting synced down to my Mac.

It seems if I could get rid of All Mail on my Mac I’d immediately free up 81GB of space. I don’t want to get rid of All Mail altogether. It’d be good to keep it around at Google in case I miss something. But I would like to not sync it down to my computer. I still need my inbox, and other Gmail functionality to work, but I’m wondering if there’s a way to stop syncing All Mail to my Mac. And, if that’s even a good idea.

I also see the option in account settings for Download Attachments, with the options All, Recent and None. I read that Recent refers to messages up to 15 months old. If I switch to Recent will that update the synced All Mail folder to remove older attachments on my Mac, or would I still need to manually remove them? This presumes that the attachments are the bulk of the issue.

Any advice will be most welcome – thank you! – Why do Mail preferences get lost on reboot?

Apple Mail, the OS bluetooth subsystem and some other applications (e.g. Fantastical) loose relevant (but not all) configuration and preferences on nearly every reboot. For Apple Mail it seems that all lost settings are stored in the file ~/Library/Containers/ I haven’t yet identified the other affected files.

What could cause the file contents to be lost on nearly every reboot? It does not happen if I hunt for it (keep rebooting), but only after using the Mac for a while.

I currently run macOS 10.15.6 on a MacBook Pro 16″ with only a few popular Apps from the App Store plus Microsoft Office.

I am a long term Mac user. The bad behavior started approximately 2 years ago after an update to macOS High Sierra (I think). The Mac became more an more unusable because of this and other strange bugs (it also started to become extremely slow, so I had to reboot regularly, loosing all settings afterwards). Repairing and even installing the OS did not help. Therefore, I got a new Mac and installed everything from scratch (no restore from a backup) and installed only very little software on the system. However, the preferences still get lost on nearly every reboot!

macos – Delay sending email by x seconds in

Gmail has a useful feature where they allow you to “undo” the sending of an email by up to 30 seconds (if I recall correctly) of any email. It does this by not sending the email for up to 30 seconds, allowing you to cancel and edit the email, or not send it at all instead.

In using on macOS, I’ve missed this incredibly useful feature. Is there a way to automatically send the email after, say, 30 seconds with the ability to cancel it before it’s sent? can use plugins, so maybe there’s a plugin for this?

Note: I am looking more for a “send after delay” rather than a “schedule send” feature, which is more streamlined and allows me to send emails normally without having to choose a time. – Mail Cannot Save Information About Mailboxes

Sorry to come on with yet another stupid question, but when I start, I’m seeing:

Mail Cannot Save Information About Your Mailboxes Because There Isn’t
Enough Space In Your Home Folder

I run a df ..

Filesystem      Size   Used  Avail Capacity iused       ifree %iused  Mounted on
/dev/disk2s5   1.8Ti   11Gi  906Gi     2%  487554 19530667326    0%   /
devfs          207Ki  207Ki    0Bi   100%     718           0  100%   /dev
/dev/disk2s1   1.8Ti  935Gi  906Gi    51% 3295438 19527859442    0%   /System/Volumes/Data
/dev/disk2s4   1.8Ti  2.0Gi  906Gi     1%       2 19531154878    0%   /private/var/vm
map auto_home    0Bi    0Bi    0Bi   100%       0           0  100%   /System/Volumes/Data/home
/dev/disk2s3   1.8Ti  501Mi  906Gi     1%      42 19531154838    0%   /Volumes/Recovery

So I see /System/Volumes/Data/home and thought that maybe that was similar to the old Solaris thing of /export/home being the same as /home. But there is nothing in that directory.

If I go to Apple –> About this Mac and look at storage, I see 1.06 TB free out of 2 TB.

This is stopping me from using my Mail client. I tried the solutions here.

None of them worked.


applescript – – compare two mailboxes?

I try to transfer 50 000 mails from an IMAP account A to another IMAP account B using but it constantly fails during the process (that takes a day or so). There is a message-id-based duplicate filter on B so I am not afraid of duplicates but it is a PITA to figure out which messages are missing (≈ 100).

Is there a way to compare two mailboxes in Script?

Google didn’t return any obvious results. Would be nice to be able to do it both using message-id but also a combination of timestamp, to/from, subject and/or size and similar. – Unable to select Gmail Important in Smart Mailbox

I have two Google email accounts — one and other managed by university.

I want to have a smart mailbox that shows important emails from both accounts.

But I am unable to do so.

The important folder from gets unselected when I click ok and reopen next time.

I run macOS Catalina 10.15.4, not sure whether its specific to my computer because of some corrupt configuration. Appreciate any thoughts on fixing this.

smart mailbox window