Open Source client for working with Microsoft Exchange?

Question

open source

Hello. The customer does not want to pay for the MS Office package, while he does not see an alternative for working in a corporate environment without Microsoft Exchange (he is ready to pay for it), incl. because of the calendar.
I am looking for a mail client in the short list for proposals to the Customer. Need "Outlook" without the Outlook price tag. :-)

Answer 1

OWA use

Answer 2

Correct answer.
There is no complete replacement.
All that I saw provide only some part of the functionality.
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For those who really need it, they have money and they will buy it.
And for those who don't have it, it's like they don't need it.
And if one of the customers asks and says that he has no money, then you should not contact him, since this rogue will not have money to pay for your services later.

Answer 3

Hehe, life hack that I'm using right now.
Thunderbird + Davmail + exchangecalendar (the development of the latter really got up at the end of 2018). davmail provides reading and sending mail through eksch (through OWA) and part of the address book functionality, exchangecalendar - it is clear that the calendar-tasks-notes and another part of the address book. Of course, not without jambs, but for free.
Although, I must say, if there is money for eksch - and there they are considerable! - then they should be found on Outlook ...

Answer 4

"Whoever sells the smell of a dish - gets a ringing from the money" (c)
Suggest to the customer to hire a development team that will write for him what he is looking for, and most importantly, then put it in open source. The working people will thank him.

Answer 5

In general, open source and free are not the same thing.

Answer 6

eM Client
And so - any client who knows how to use EWS

Answer 7

The functionality close to Exchange in the world of open source is Zimbra. (again there is a community version, free and with support for money)
With my client.
To connect mobile clients, it uses reverse-engineered (but this is not accurate) ActiveSync from Exchange.
In general, everything is there, GAL, OAB, Folders, notes, calendar ...
PS
But of course you will have to finish it yourself on your own if you encounter a customer's foolishness.