For property managers

For property managers: tenants on one side, owners on the other, and both write to you

The heating is off. When is the plumber coming. Is my lease being renewed and at what. Why is there a deduction on my statement. What do I have to do before I hand the keys back. A property manager answers the tenants and reports to the owners, and the same leak produces one email to each, in two different registers, before the invoice is even in. Multiply by every unit under management and it is an inbox that never empties.

MailTwin writes those emails from your notes. You type the points, it writes the finished message in your own words, and you read it and send it.

What that looks like on a Monday

Select the message in Apple Mail, type what the reply needs to say, and MailTwin writes the complete email into the reply window — greeting, every point in full sentences; Mail appends your own signature.

You type	You get
plumber booked Wednesday 8–12, tenant in or leave a key with the neighbour, he rings 30 mins before	A maintenance confirmation with the window, what the tenant has to arrange, and the one detail that stops a missed visit
renewal at 1,450 from 1 July, twelve months, answer needed by the 15th, otherwise notice period applies	The renewal offer with the figure, the term, the deadline and the consequence, stated once and plainly
to the owner: leak fixed, 280 for the call-out and the part, invoice attached, comes off this month's statement	An owner update in the owner register, short and about the money, with the paperwork referred to properly
move-out inspection Friday 10am, all keys and fobs back, clean to the attached checklist, deposit released within ten days of that	The move-out email with the four things they need to do, in order, so the deposit conversation is a short one

None of those is hard. That is the point. The evening goes on the forty easy ones.

Two audiences, one inbox

You do not write to a tenant the way you write to an owner. One needs reassurance and instructions; the other needs the figure, the invoice and a sentence about what happens next. Most email tools hand you a tone slider for that. MailTwin learns voice separately for every mail account, from that account's own sent mail. If tenant correspondence and owner reporting go out of separate addresses, each keeps its own register and switching mailbox switches the voice. If everything goes out of one address you get one learned voice, and you steer the individual email by what you type.

Rents, deposits and dates

A renewal email with the wrong rent in it is a dispute. When MailTwin rewrites a draft you have already written, a validator checks the result before it reaches you and rejects it if a number, a date, an amount, a link or an email address has changed. That runs every time.

What it cannot do is judge whether a new sentence is true. It does not know the ledger. Type 1,450 when the owner agreed 1,400 and you will get 1,450 in a well-written sentence. Reading the draft before it goes is still the job, and nothing sends without you.

The maintenance thread that has been going since spring

One persistent leak generates a thread with the tenant, the owner, two contractors and the insurer, and by the time it is resolved nobody can remember who agreed to pay for what. MailTwin summarizes the thread and pulls out the open actions, which is what you need before the owner's next call. It also improves a draft you have already written, including inside Mail's own compose window, and translates, for the tenant or the owner who writes in another language.

The honest version of the time saving

Christopher Naas, who makes MailTwin, says it saves him an hour or more on a busy email day. That is his experience, not a promise about a portfolio inbox, and anyone quoting a precise figure is guessing. What holds is where the time goes: not into the difficult email about a deposit deduction, but into the forty confirmations and updates around it.

What it will not do

It does not connect to your property management software, your rent ledger, your maintenance tickets or a portal, and it does not know a unit's status unless you type it. It will not read your inbox on its own, answer anyone without you, or send anything you have not looked at; there is no autonomous mode and no scheduled sending. It is macOS 13 or later only, Apple Mail only, with no iPhone or iPad app, so the emergency you read on your phone at seven waits until you are at the Mac. It needs two macOS permissions on the first run, Automation for Mail and Accessibility, which is a few minutes of clicking in System Settings and cannot be automated away, because Apple deliberately does not let an app grant itself access to your mail. And if your replies are mostly one line, it will not help much. It is built for the paragraph.

Where tenant and owner correspondence goes

MailTwin has no AI of its own. You choose one of nine engines and supply the key. Three of them, Apple Intelligence on macOS 26 or later, Ollama, and a local OpenAI-compatible server (oMLX, LM Studio, llama.cpp), run on the Mac itself, and with those the message is never transmitted at all. With a cloud provider, the request goes from your Mac straight to that provider, along with a short sample of your own sent mail so the reply sounds like you. Your voice index stays on the Mac. Nothing goes to MailTwin, because there is no MailTwin server and no MailTwin account for it to go to.

For the data protection answer you will eventually have to give an owner: the sent mail your voice is built from is read and stored locally, under your own user account, and if your rule is that tenant data does not go to a cloud AI service, the on-device engines are a complete answer.

For management associations and franchise networks

If you run a professional body or a franchise network and want to look at this properly before your members hear about it, write to [email protected] and licences for the office will come back, no conditions and nothing expected in return. Endorsements are not asked for and not implied. MailTwin is made by Smilodon AS, a one-person company in Norway, and the person who answers that address writes the code.

Common questions

Does MailTwin connect to my property management software?

No. It does not read your management system, your rent ledger, your maintenance tickets or a portal, and it will not look anything up. You type the appointment, the figure or the date in a few words and it writes the email around them. It only knows what you typed and what was in the message you selected.

Can the tenant emails and the owner emails sound different?

If they go out of separate accounts in Apple Mail, yes. Voice is learned separately for every mail account from that account's own sent mail, so a tenant-facing address and an owner-facing address each keep their own register, and switching mailbox switches the voice. If everything goes out of one address you get one voice and steer the individual email by what you type.

Could it change a rent figure, a deposit or a date?

When it rewrites a draft you have already written, a validator rejects the result if a number, date, amount, link or email address has changed. What it cannot do is judge whether a new sentence is true, so a wrong rent figure you typed comes back written out neatly. Read every draft before it goes. Nothing sends on its own.

Does tenant and owner correspondence go to a third party?

You choose the AI engine from nine. Apple Intelligence on macOS 26 or later, Ollama, and a local OpenAI-compatible server run on the Mac itself and transmit nothing. With a cloud provider the request goes from your Mac straight to that provider under your own key, with a short sample of your own sent mail for the voice. There is no MailTwin server and no MailTwin account in the path.

What does it cost, and is it per seat?

A one-time licence with a 30-day full trial and no card to start, and a five-licence pack for an office. The engine is separate: the three on-device engines cost nothing to run, and a cloud provider bills you directly for what you use, usually a few cents a day at ordinary volumes. The app shows a running total.

Try it on a month of maintenance

Thirty days, every feature, no card. A month with a renewal run and a burst pipe in it is the only honest test.

Download MailTwin →

Other guides

Weighing it against something else? Best AI email assistant for Mac in 2026 compares six options and says who should pick each one.