Mail Settings not working after 15.5 upgrade

[Kleanthis Savva]

So everything was working fine then we updated our System to the latest version .
Now we have an issue configuring emails from our exchange server . The error i get in the logs is :

A call to SSPI failed, see inner exception. ---> System.ComponentModel.Win32Exception: The client and server cannot communicate, because they do not possess a common algorithm ===> When using SSL/TLS

0008|Excpt|System.NotSupportedException: No compatible authentication mechanisms found. ---> When not using TLS/ SSL

I had it configured without SSL/TLS in the past and it was working fine. Now after 15.5 update it does not.

Any help is appreciated.

 

[gustavskii]

Hello @Kleanthis Savva

I just had similar issue
I got help:
3CX started enforcing TLS 1.2. That could be your issue, especially if you are using alternate ports. (Other than 465. Even 587 was an problem for them.)

So set your TLS connection port to 465 and it will work

 

[Goga]

I have the same issue , but my question is if customer not using SSL or TLS, then it should work .
But after update V15.5 SP3 , normal is also not working.

any help will be appreciated.

 

[Kleanthis Savva]

Please fix this , this is very critical.

 

[Kleanthis Savva]

A new hotfix came out but no resolution for email issues yet . Anyone have a solution ?

 

[YiannisH_3CX]

Hello @Kleanthis Savva

There is nothing to fix on our end as the message you are getting originates from your mail server. You need to solve your authentication methods to get things working. Alternatively you try gmail as your mail server to see if this works for you. https://www.3cx.com/blog/docs/gmail-mail-server/