The best way to manage multiple Gmail accounts on a Mac

Three Gmail accounts is the point where the browser stops helping. A reply goes out from the wrong address. A link opens in the account that happens to be signed in first and shows a permission error. A Drive file that definitely exists cannot be found, because it belongs to the other one. None of these are Gmail bugs. They are all the same underlying behaviour, and Google documents it.

The decision is not really about which app to use. It is about whether the accounts get merged into one place or kept apart in separate places, and two of the routes for merging them are being withdrawn. What follows states which arrangements Google still supports, read on 26 September 2026, and what each one costs.

The default account is the actual problem

Google's multiple sign-in feature lets several accounts be signed in at once and switched from the profile menu. It works, and it carries a caveat that explains most of the confusion it causes. Google's help page states that when several accounts are signed in at the same time, it sometimes cannot tell which account is in use, and gives opening a new browser window as the example.

In cases like these, Google might apply settings from your default account, like its Web & App Activity and Ads Personalization settings. Source: support.google.com

The default account, Google states, is in many cases the one signed in first. That single rule produces the whole family of symptoms. A document link opens under the default account and returns a permission error. A calendar invitation lands in the wrong place. Activity and advertising settings from the default account can apply across the others.

Multiple sign-in shares one browser session between accounts, and a shared session cannot be told apart. No amount of care in clicking fixes it, because the ambiguity is created when a new window opens, not when a link is clicked.

This is the fact that decides between the two families of answer. Merging accounts into one view keeps one session and therefore keeps the ambiguity. Keeping them in separate sessions removes it and costs something else instead.

Two of the routes for merging are closing

The traditional way to read several accounts in one inbox was to have Gmail fetch the others. Google's help centre now states that this is ending.

Gmail is removing Gmailify, which applied Gmail features such as spam protection and inbox categories to a third party account, and it is removing Check mail from other accounts, the setting that pulled messages in over POP. Google's guidance for anyone relying on it is to set up automatic forwarding at the other provider instead, or to add the account in the Gmail mobile app, which uses IMAP.

A second route is narrowing on a fixed date. The help page for sending from a different address states that starting January 2027, Gmail will no longer support the Send as feature for third party email addresses such as @yahoo.com or @outlook.com, and that the change does not affect Google Workspace aliases or other Gmail addresses.

What remains is worth knowing precisely, because it is generous. Gmail still allows sending from up to 99 different email addresses, and the Send as route still works for Gmail addresses and Workspace aliases. Setting it up needs a verification message on the other account, and one detail is easy to miss: sending from another address by default requires changing both the default From address and the reply-to address, otherwise replies come back to the original Gmail address.

The direction of travel is clear enough to plan around. Consolidating third party mail into one Gmail inbox is becoming a forwarding arrangement rather than a Gmail feature. Consolidating several Gmail or Workspace accounts is still supported, and aliases are safe.

What each arrangement actually costs

Arrangement	Accounts stay apart	Main cost
Multiple sign-in in one window	No	Default account applies when Google cannot tell which account is in use
Chrome profiles	Yes	A separate window and a separate set of extensions per account
One window per web app, separate sessions	Yes	More memory than tabs, and a short setup
Delegation	Yes	Recipients see the delegate's address, and several Gmail features are unavailable
Forwarding into one inbox	No	Replies need the correct From address set manually
Desktop mail client	Partly	Loses the Gmail web interface, labels and search behaviour

The table is the whole decision in one view. The routes that keep accounts apart all cost window management. The routes that merge them all cost accuracy about which account an action belongs to.

Delegation is the route most people have not tried

For a shared inbox or an assistant, Gmail has a feature built for exactly this, and its limits are documented rather than guessed at.

A delegate can read, send and delete mail in another account. Google states the ceilings directly: a personal @gmail.com account can add up to 10 delegates, a work or school account up to 1,000, and with typical use 40 delegates can access an account at the same time. The invitation expires after a week, and it can take up to 24 hours before a delegate can use the account.

Two constraints decide whether it fits. When a delegate sends a message from the account, their own address appears, which is correct for an assistant and wrong for a shared support address that should look anonymous. And a delegate cannot be added to an alias, because an alias is not a Google Account.

The feature list unavailable to delegates is longer than most people expect. Google names access to Google Account settings, adding attachments from Drive, adding photos from Google Photos, adding to Tasks, autocomplete, autocorrect, Chat in Gmail, client-side encryption, emoji reactions, Gemini in Gmail, Meet in Gmail and Smart Compose. For reading and answering mail on someone's behalf that is fine. For working in the account all day it is not.

Delegation is the right answer for accounts that belong to someone else and the wrong answer for accounts that all belong to the same person. A freelancer with three of their own addresses gains nothing from it.

Chrome profiles, and where they stop

The standard advice for keeping accounts apart is a Chrome profile each, and it is sound. Google describes profiles as keeping bookmarks, history, passwords and other settings separate, and names work and personal separation as one of the two intended uses.

There are two costs, and only one of them is usually mentioned. The first is that each profile is a separate window with its own extensions, its own pinned tabs and its own set of everything, so three accounts means maintaining three browsers that happen to look alike. Setting up an extension across all of them is three jobs.

The second is stated by Google on the same page: anyone with the device can switch to any other profile on it and see the sites that were visited. Profiles separate data, not access.

What profiles do not give is per application structure. Inside a work profile, Gmail is still one tab among thirty, so the original complaint about a buried inbox survives the whole exercise. Profiles fix which account is in use. They do not fix where the inbox is.

What a desktop mail client changes, and what it does not

The other standing answer is to stop using Gmail in a browser and put every account into one mail client instead. Apple Mail, Outlook and Thunderbird all do this, and Google supports it, with two things worth knowing first.

Authentication has changed. Google's help centre states that Gmail no longer supports third party apps or devices that require sharing a Google username and password, and directs people to look for a Sign in with Google option instead. Anyone carrying a configuration from several years ago, with a password typed into the client, is on a route that no longer works. The same page notes that since January 2025 the option to enable or disable IMAP has gone, because IMAP access is always on.

The gain is genuine: one window, one unified list, and every account reachable without switching sessions, which sidesteps the default account problem entirely. Mail arrives in a native app with native notifications, and search covers all accounts at once.

The loss is also genuine and shows up within a day. Labels become folders, and a message with three labels stops behaving the way it did in Gmail. Gmail's search operators are replaced by the client's own search. Features that live in the Gmail web interface, including snooze behaviour, Smart Compose and anything Google adds later, are not there. Google's own troubleshooting list for this route includes a "Too many simultaneous connections" error, which is what several clients on several machines against one account produces.

The honest summary is that a mail client is the right answer for someone whose accounts are only mailboxes, and the wrong answer for someone who also lives in Drive, Calendar and Chat under those same accounts. Mail is rarely the only thing an account holds.

Matching the arrangement to how accounts actually behave

The pattern in all of the above is that accounts are per session, and applications are per window, and the browser was built to treat both as tabs. A browser that keeps each web app in its own window closes that gap. Each inbox gets a window, each window keeps its own session, and the question of which account is default stops being a question, because there is no shared session for Google to guess about.

The practical difference shows up in the small moments. A keyboard shortcut goes to the work inbox rather than to whichever tab was last open. A notification identifies which account it came from. A link clicked in one window stays in that window's session. The Workspaces page sets out how the grouping is arranged, and the Supported apps list covers which services are prepared for this out of the box, Gmail among them.

The cost is real and worth stating. Separate sessions use more memory than shared tabs, and the initial setup takes a few minutes per account. For two accounts the profile approach is probably enough. For four or more, maintaining four parallel browsers is the larger tax. Anyone comparing the tools built for this can start from Compared with Wavebox and Compared with Shift, which set out how the same problem is handled elsewhere.

What to change first

Open each Gmail account and check the Accounts tab for anything under Check mail from other accounts, because Google is withdrawing it and forwarding at the source provider is the replacement. Then decide one question: whether the accounts all belong to one person, which points to separate sessions, or to different people, which points to delegation. If the answer is separate sessions and there are more than three, give each inbox a window of its own with something like SpaceDeck rather than running a browser per account.