複数のGmailを切り替える: the setup order that holds up

Setups for several Gmail accounts tend to fall apart in the same way. The tool gets chosen first, the accounts get added in whatever order they come to mind, and three weeks later the arrangement is being patched: a bookmark that opens the wrong inbox, a signature that belongs to the other company, a notification with no way to tell where it came from. None of those are tool problems. They are ordering problems. Several of the decisions involved are one-way, and making them in the wrong sequence means redoing the ones that came before.

Why the sequence is not interchangeable

Two decisions in this process set constraints on everything after them.

The first is sign-in order. Google states the rule directly: the default account is the one signed in with first. That single fact decides where every link without a session index lands, for as long as the browser session lasts. It is not a preference buried in settings that can be flipped later. Changing it means signing out of every Google account and signing back in deliberately, which invalidates any bookmark that points at a specific /u/N/ index.

The second is the unit of separation. Whether the boundary sits at the tab, the window, or the application determines what is even possible afterwards. A setup built on tabs cannot later be given per-account notification origins without rebuilding it. A setup built on windows can absorb new accounts without disturbing the existing ones.

Everything else in this article is reversible. Signatures, filters, aliases, and app choices can all be changed on a Tuesday afternoon with no consequences. So the order below front-loads the decisions that are expensive to undo and leaves the cheap ones until the end.

Step 1: name the boundary before choosing anything

Write down what each separate space represents. There are two common answers, and they behave very differently.

Separation by identity means one space per legal or social identity: this company, that client, personal life. The boundary matches how accounts are actually issued, so it stays stable. A client's Google Workspace account, their shared Drive, their project tool, and their chat all belong to the same space because they all belong to the same identity.

Separation by activity means one space per kind of work: writing, admin, meetings, code. It feels tidier on paper and it fails quickly, because a single account appears in every space. The same Gmail account is needed for writing, admin, and meetings, which means the account cannot live in one space, which defeats the point.

List what belongs to each space, not just the Gmail account

The Gmail account is rarely alone. Write out everything that shares its identity: the Drive account, the calendar, the chat workspace, the project tracker, the invoicing tool, the password vault entry. If two spaces both need the same tool under different logins, that tool is a separation requirement and belongs in the notes, because it will be the thing that determines whether browser profiles are sufficient or not.

This list also exposes the accounts that have no identity of their own. A shared vendor login used by three clients does not belong to any one space, and pretending otherwise is how a boundary gets broken two weeks in. Park those in whichever space uses them most and accept that they are an exception.

Count the spaces before going further

Most people who do this exercise end up with between two and four spaces. If the count comes out above six, the boundary is probably drawn by activity rather than identity, and it is worth redoing before any software is installed. A high count is the single best predictor of a setup that gets abandoned.

Step 2: decide which account absorbs stray links

This is the decision that pays for itself. Every URL that arrives without a session index goes to the default account: links from chat apps, calendar invites opened from a notification, search results, anything clicked outside the browser.

So the question is not which account is most important. It is which account should receive things that arrive with no context attached. For most people that is the main work account, because a work link arriving in a personal inbox is a mild annoyance while the reverse can mean a client sees the wrong identity.

Once the answer is clear, execute it: sign out of all Google accounts, then sign in with the chosen account first, then add the others. Do it before building bookmarks, because those bookmarks encode the resulting order and will break if the order is redone later.

Step 3: give each identity its own storage area

Only now does the tooling question arrive. The minimum viable boundary is a browser profile, which Chrome describes in one sentence:

With profiles, you can keep all your Chrome info separate, like bookmarks, history, passwords, and other settings. Source: support.google.com

Chrome creates a profile through the avatar in the top right and Add Chrome profile, then asks for a name, photo, and colour scheme. Safari added the same concept in Safari 17, with each profile holding its own tab groups, history, favourites, and extensions.

Three details are worth getting right at creation time rather than later.

Give each profile a colour that is actually distinguishable at a glance, not two shades of blue. The colour is the only signal available from a distance. Name the profile after the identity rather than the account, so it reads "Client A" instead of an email address, which stays readable when the address changes. And decide now whether password manager and extensions are installed per profile or everywhere, because moving extensions between profiles later means re-authorising each one.

Decide how a space gets opened

A storage area that takes four clicks to reach will be bypassed. On macOS the options are a Dock entry per profile, a Spotlight-reachable application, or a keyboard shortcut through a window manager. Pick one and set it up at the same time as the profile, not later, because the habit forms in the first week and a habit of opening the wrong window is expensive to unlearn.

The related question is what happens to the previous space when a new one opens. Leaving every window open defeats the separation, since all of them stay visible in the app switcher and all of their notifications keep arriving. Closing them entirely means reloading web apps on every switch. Most people settle on keeping one space visible and the rest hidden, which is the behaviour most purpose-built tools in this category implement by default.

Step 4: settle addresses before settling apps

Sending from an alias is often used to avoid switching at all. Google allows a great deal of this: emails can be sent from up to 99 different email addresses. Each one requires a verification step, where a confirmation message is sent to the address being added and the link inside it has to be clicked from that account.

Two constraints belong in the plan.

Recipients do not always see a clean result. Google notes that depending on the receiving service, a message may appear as "From [email protected] on behalf of [email protected]", and the original address can also surface through out-of-office replies and automated filter responses. For client-facing mail this matters.

More importantly, one whole category of alias is ending. Google has announced that from January 2027 the "Send as" feature will no longer be available for third-party addresses such as @hotmail.com and @yahoo.com, along with Gmailify and POP fetching from third-party accounts. Sending from other Gmail addresses and Google Workspace aliases is explicitly unaffected. Any setup being built now should treat third-party send-as as temporary.

The consolidation route has a ceiling too. Google states that up to 5 email addresses can be added to a Gmail account, which is comfortable for two accounts plus a domain address and tight for anyone holding a mailbox per client.

Step 5: route links and notifications last

With identities, defaults, storage areas, and addresses decided, the remaining work is traffic direction.

macOS sends every link clicked outside a browser to one default browser. That single setting defeats a lot of otherwise careful separation, and it is the reason browser profiles alone do not fully solve the routing problem: the link goes to the default browser, and from there to whichever window happens to be frontmost. Tools that bind an account to a window exist mainly to close this gap, and pages such as Features describe what that binding covers.

Notifications deserve the same treatment. A badge that cannot be traced to an identity produces the reflex of checking everything, which is the exact cost this whole exercise is meant to remove. Whatever arrangement is chosen, the test is simple: can the origin of a notification be identified without clicking it.

macOS Focus modes can carry part of this load without any additional software, since a Focus can allow notifications from a specific application and silence the rest. That works cleanly when each identity has its own application. It works poorly when every identity lives inside one browser, because the Focus can only see the browser, not the account inside it. This is the practical reason the separation unit chosen in Step 1 keeps reappearing.

Mobile is a separate system and should be set up separately rather than mirrored. The Gmail app holds several accounts through its own mechanism and does not inherit the desktop default. Deciding which account the phone opens by default is a second, independent decision.

Where the tools differ, and what each costs

Published prices as of September 2026, which are worth checking against the vendor page before committing:

Tool	Free tier	Paid	Platforms
Browser profiles	Included	None	macOS, Windows, Linux
Ferdium	Entire app, Apache-2.0	None	macOS, Windows, Linux
Rambox	Unlimited apps, up to 2 instances per app	$7.00 per month or $70.00 per year	macOS, Windows, Linux
Wavebox	Basic plan after a 7 day Pro trial	$8.33 per month paid annually	macOS, Windows, Linux
Shift	5 Spaces, 10 apps per Space	$199.99 per year	Desktop

The pattern is consistent. The free options separate storage but leave routing to the operating system. The paid options add account-bound windows, unified search, and per-account notification handling. Whether that is worth a subscription depends entirely on the link-routing count from Step 2. A comparison such as Compared with Rambox is useful mainly for seeing which side of that line a given product sits on, and Supported apps matters more than feature lists if the daily set includes anything unusual.

What to change first

Do Step 2 today, because it takes ten minutes and fixes the most frequent failure without installing anything. Leave the tool decision until the boundary from Step 1 is written down and the number of spaces is settled. If the count lands at three or more and routing is still the daily irritant, SpaceDeck is one of the macOS options that binds accounts to windows rather than to tabs.