Desktop clients
Phone clients
Migration and sync tools
OxiMail Sync, the desktop file sync client
OxiMail Sync keeps a folder of the computer in step with the person’s files on the server. It is not released yet; the results below are for the version that will be.
Not tested yet: Windows.
The disk image is not signed by Apple yet: macOS asks to confirm the first opening, and asks for the keychain password again after each update. Both go away once the app is signed.
Clients that route mail through their vendor
An IMAP client normally talks to your server and to nothing else: the password stays on the device, and the mail travels between the device and your server. Some clients put their vendor’s servers in the middle, to send notifications, to sync faster, or to offer features that run in their cloud. The vendor then holds the password or copies of the mail, under its own terms and the law of its own country, and it can read the mailbox without anyone at the device. For mail that must stay between your server and your devices, that is a third party you did not choose.How we measured it
OxiMail records every connection with its account and the address it comes from. During each test we compared those addresses with the test device’s own. An address that was not the device’s was looked up in the internet registries (RDAP) to find who holds it. The test accounts were used by our test machines only, so any other address that signs in is a third party.What we found
Every other mail client on this page connected to IMAP and SMTP from the test device only: Apple Mail, Thunderbird, Thunderbird for Android, FairEmail, the Gmail app with an IMAP account, KMail and Geary. No address outside our test machines appeared for their accounts.
What to choose
- For mail bound by professional secrecy, use a client that talks to your server alone: one of those listed just above.
- If people use Outlook for Mac, they choose Sync directly with IMAP, never Sign in, when they add the account. Tell them before they set it up: the button they are offered first is the other one.
- Do not let Spark, or any client that asks to create an account with its vendor before it adds a mailbox, near such mail. That request is the sign that the vendor keeps something of the mailbox: check its privacy page before anything else.
- A person who already used such a client changes the password of the mailbox afterwards, and deletes the account they created with the vendor (for Spark, in its settings), so that the vendor holds nothing that still works.
Known limitations
These are open defects of the server, found with the clients above. Each one is being tracked; this list shrinks as they are fixed. Mail- Geary and mbsync synchronize no message. The server sends both clients a piece of information they did not ask for, and they stop. Until it is fixed, use another client.
- Drafts saved over IMAP are rebuilt by the server instead of being kept exactly as the client wrote them. With a plain text draft nobody sees a difference. A Thunderbird draft with a text file attached can show the attachment’s text as the body in another client, and a draft copied by imapsync keeps the copy date instead of its own.
- Marking a message for deletion in one folder marks its copies in other folders too (Thunderbird’s “delete” without moving to the trash).
- Two clients changing the same message at the same instant can lose one of the changes: a flag set by one, or a move made by one, can be undone by the other. Deleting a folder that still holds messages can leave those messages out of every folder.
- A message to an address that does not exist on your own domain is accepted when sent, then returned to the sender as undeliverable, instead of being refused at once.
- Invitations sent by OxiMail show the raw calendar text under the message in the Gmail app. The invitation itself is valid and other clients show it normally.
- On a Mac or an iPhone, installing the configuration profile of a second address of the same domain removes the first one, with all its mail, calendar and contacts settings. Until it is fixed, add the second address by hand in System Settings, Internet Accounts.
- Apple Mail uses the name of the Mac’s user account as the sender’s name, because the profile does not carry the person’s name. Change it in Mail, Settings, Accounts.
- Outlook for Mac can show a sender’s accented name wrongly (
Exp√©diteurforExpéditeur), in a message whose sender wrote the name without encoding it, as some senders do. The message itself is intact, and other clients show the name correctly. - One mistyped password can count as several failures: macOS retries it at once, four times. Spark, while it adds an account, first tries the user name without the domain, which counts as four more failures even with the right password. A second mistake can then block the device’s address, which is the address of the whole office behind the same router, for 60 minutes.
- Two events with different identifiers in one file: only one is kept.
- An event in a time zone that is not a standard IANA name (some clients write their own definition) is read as UTC, so it can appear at the wrong hour.
- On a rewritten event, the request for a reply and the role of each invitee are dropped, and a “confirmed” status is added when none was given.
- A task reminder dismissed in Thunderbird can ring again after the next sync.
- On a Mac, Contacts shows the addresses the server collected instead of the person’s address book, as soon as the account has sent mail. That book is read-only: the person’s own contacts no longer appear, and the contacts created on the Mac stay on the Mac. macOS syncs a single address book per account, and picks the wrong one.
- A contact’s photo added in Thunderbird is dropped.
- Email address types can change: an address with no type becomes “work”, and the preferred address or phone number loses its preference.
- Address books are named
personalandderivedin clients that show the collection name.
How each client finds its settings
Most clients can set themselves up from the email address alone. They do not all look in the same place, so publish both the DNS records and the auto-configuration names listed in Autodiscovery, and make sure the certificate coversautoconfig.<your domain>.
The values to type by hand, with
mail.example.com standing for your server:
The user name is always the full email address.
Behaviour of the clients worth knowing
- New mail arrives in about two seconds in Thunderbird for Android, FairEmail and Apple Mail, which keep a connection open (IMAP IDLE). Calendar and Contacts on macOS only check the server from time to time, or when something changes on the Mac. The Gmail app does not: for an IMAP account it checks every 15 minutes at best.
- FairEmail looks for the sent message on the server before saving its own copy in Sent. OxiMail does not file sent mail by itself, so FairEmail saves the copy, which is the expected path.
- Outlook for Mac and Spark send something of the mailbox to their vendor: see Clients that route mail through their vendor. Spark’s “Set aside” also creates a
Laterfolder on the server. - Changes made in one client appear in the others: tests ran two phone clients and a script on the same mailbox at once, and every flag, move and deletion reached the other clients.