Sync multiple calendars in one

Copper Contributor

Hello guys,


I'm currently trying to find a solution to implement in the company I work (I'm the IT Admin), so...


Our administrative - the person who manages all the calendars from the CEO - needs a unified calendar from 3 different mailboxes (2 outlook and 1 gmail), I have extensively looked for ways to do this but always end up in manual procedures which don't make sense or paid add-ins. 


Ideally, every appointment/meeting received in all 3 CEO's mailboxes would sync directly to the administrative's PC.


Just to picture all the calendars from the mailboxes below:






into account:



Is there a way to do this?


Is it possible to create an automatic appointment/meeting redirection to different calendars?


Thank you very much in advance!



29 Replies

Try CodeTwo Outlook Sync tool.




Thanks Konrad!

But we are not looking to spend money on this...

Any other suggestion?

Normally you can import data from one outlook to another, but in fact there is no synchronization between them without external tools.

Understood...too bad we won't be able to do this without using 3rd party tools.

Anyways, thanks for your input here Konrad!

If you want to sync data from multiple mailboxes (eg calendars) into one, you could give Exchange Sync by Connecting Software a go:


If you don't want to spend any money on this, you need to resort to means offered by the mail platforms used. GMail is the odd one out, I'm afraid there's no 'automated' process offered out of the box except for following strict manual procedures. If it's a one-way sync, you could develop something yourself, eg clear the overview calendar, and import/merge the source calendars using imap (as GMail doesn't support EWS).


Since the tools mentioned solve a business problem for you, in addition to being supported tools, there is a business case making the price worth compared to manual labor.

best response confirmed by IT MEC Group (Copper Contributor)

Maybe MS Flow can help. Check this templates.
It is hard to sync calendars in both ways, and in outlook there is no trigger 'When event is deleted', but all new meetings you can send automatically to one calendar.

Like IFTT, Flow would be an option - initial loading of the overview calendar being a one-time manual sync, and maybe repeat periodically to make sure the calendars are kept in sync (as it's one-way)

Wow cool Dawid! This helps a lot...

Thank you very much!

Hi JC,


Konrad mentioned one of our paid solutions (thank you Konrad!), but we also offer freewares.


For your scenario, you may want to take a look at CodeTwo FolderSync Addin:


It's an Outlook plugin that lets you sync pairs of folders.


Give me a shout if you have any questions!


Best regards,


The CodeTwo FolderSync Addin seems to only offer a manual sync at a push of a button.


Are there any solutions for setting up an automatic sync between 2 Outlook calendars?

To sync two Outlook calendars automatically, check CodeTwo Outlook Sync mentioned by Konrad. It's freeware now.


All the best,


I tried a lot of thing out there.... but it doesn't work for us...

The thing is out company work for a lot of clients and often these clients have there own O365 environment with exchange e-mail. So when I open up my outlook 2016 desktop client I have like 6 agenda's. 

- 1 O365 exchange agenda from our company

- 3 O365 exchange agenda's (different clients)

- 2 icloud agenda's (personal)

By using the overlay mode in outlook 2016 it from me as a user not a problem. But within our company it's quite difficult to get an appointment with direct colleagues using the planning assistent functionality in outlook 2016 because then only the appointments within the company O365 agenda are visible.  So we thought it could be a solution that we install a tool on client site (server side is not an option because we are not admins of the O365 environments of out clients) which will merge all appointments in 1 agenda, it would be great if somehow the appointment colours would be left in tact our that there is another way to recognize from which original agenda the appoint is.

We are searched hard for a tool or solution but didn't found one. Forwarding every single agenda item is not really a solution and takes even more hassle then ping-pong mailing with a colleague for finding a timeslot. Anybody any thoughts on this? Thanks and best regards



Have you been able to find a solution. I am currently in the exact same situation, and would like to find an automated solution that would ocuppy the time slots without copying any other details. This way I can also avoid sharing confidential information that might be in the meeting title or location, etc.



Well, me too having the same issue. In addition, one account being a Groupwise account, go figure.
I wonder how one does manage such situations. Best (non technical) practice sharing would be nice.

On the technical side, one might try to do something with Microsoft Flow. Not perfect and quite ugly, but at least half-automated. Since Flow is running per O365 account, you need a flow making a copy of each new appointment, tag it with a keyword, and invite the destination calendar without requesting a reply.
I'm sure someone having a much closer understanding of calendars, flows and such, might be able to create a custom flow that does it without having to create a local copy of each meeting in each calendar. My sledge hammer approach is ugly.. told you.

It's not working for icloud agendas, though. At least I have not seen a flow icloud calendar connector. I do not know much about apple calendars on icloud, but perhaps there is a way with flow webhooks? If yes, that would open up other possibilities too, right?

There are some iOS calendar applets on IFTTT which might work with the Office 365 calendar applets. But again, you have to try. I am far away from using apple stuff ;)

If someone out there is reading and is going to work on a test or implementation with flow, let me know. I am interested to contribute. Even if I am only able to test...



I am trying to get Exchange room accounts (calendars) to sync into a single calendar in Sharepoint.  However, I will settle for being able to subscribe to the room calendars and have them each update into their own block on a single sharepoint page.  I am not an administrator for the room calendars where each "" would populate on the page.  I don't need to be able to submit a request, only display who has scheduled the room.  While I can do this in Outlook 360 by overlapping all the calendars, it is very hard to read, and I don't expect my team to replicate my methods, but I do want them to check a master calendar so that they can prepare rooms as they are scheduled.  Any ideas?

I'm also trying to sync 2 calendars. We have executive offices that we are installing Polycom Trio's in. You can sign into a Skype for Business account on the device which then lets you join your meetings with One-Touch. However, we would have to constantly update ever device whenever they changed their passwords. Instead, we want to create a 2nd account that is the room. The exec's calendar and the room calendar should sync and be the same. We can kind of get there using Rules but it doesn't work 100%. 


The CodeTwo Exchange sync looked great until we found out they only work in an on-prem environment. We use Exchange Online so their product doesnt' work for us. Has anyone else had any luck syncing 2 calendars otherwise?

Same problem for us with no solution yet.


Our situation is that we are one of 2 vendors working with a client.

All 3 organizations have Office 365. Most of us in the 2 vendor companies have acquired accounts in the client's org but all of our email and meetings get sent to and from our vendor accounts—so though we can see calendars for our client colleagues, we can't see each others' calendars.


If we could automatically sync our vendor account calendars with our corresponding client account calendars—everyone could then always see current calendars of everyone on the project through the client accounts.


One may ask, "Why doesn't everyone just use their client addresses for everything on that project?" The problem with that is actually that we're also using Teams but our client doesn't have everything we'd need enabled on their instance, so we're using one of our vendor Teams instances as the working in progress home for the project meetings, messaging, and file share. If we all just used our client accounts, they're all treated with Guest permissions which have many features unavailable and we'd be stuck in the virtual lobbies of our own meetings.


So much cumulative time is wasted every day, just asking when we have open time. It is currently 2019, can't this situation be solved?

I have found a solution for syncing multiple office 365 calendars from different accounts and domains, by using extra calendars as an in-between and by using a free and open source plugin called CalDav Synchronizer (


The way I solved it is in 3 steps:

1. I have a sync profile for 365 Calendar A with a Nextcloud calendar A which I host my self (but you could also use a Google Calendar A for this), only for events with category A or no category. (replicate sync profile) For every event synced this way, the category color in Outlook is assigned which corresponds to category A (make sure to set the correct color manually in Outlook)

2. Then I have another sync profile in the plugin for a different 365 Calendar B (within a different domain), which imports new and edited events from Nextcloud calendar A, but only for events with the before mentioned category A, and again, assign the category color of category A. (merge sync profile)


3. Repeat these steps for reverse sync, so use 365 Calender B, Nextcloud calendar B, and category B (with a different color) in step 1, and 365 Calendar A an Nextcloud calendar B in step 2.


The categories are used to prevent an infinite loop of syncing the same event back and forth.


Cons: This is a local solution, run as an Outlook Plugin on my laptop, so it only works if my computer is turned on and Outlook is running. Sometimes the sync pop-up hinders using outlook for a few seconds.

Pros: It can run automatically and instantly on every event change or event addition and/or only on a defined interval. If you want, you can set copied items as 'private', so the details are protected.

See also:

Hope this helps.

@KamiA Thank you for your suggested solution. That looks like a clever, free way to get sync working.


Unfortunately for me I'm also looking for something that works cross platform, since most of the time I'm not using Windows to do my work. I might try to get this working in a Windows system, just for this, but otherwise my search continues.

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best response confirmed by IT MEC Group (Copper Contributor)

Maybe MS Flow can help. Check this templates.
It is hard to sync calendars in both ways, and in outlook there is no trigger 'When event is deleted', but all new meetings you can send automatically to one calendar.

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