==== Required information ====
- iRedMail version (check /etc/iredmail-release): 0.9.2
- Linux/BSD distribution name and version: Ubuntu 15.10
- Store mail accounts in which backend (LDAP/MySQL/PGSQL): MySQL
- Web server (Apache or Nginx): Apache
- Manage mail accounts with iRedAdmin-Pro? Free
- Related log if you're reporting an issue:
====

Hello, I'm having a problem. I try to connect to my mail server with foxmail, thunderbird and android, but i can't send any mail messages,  but i can receive the messages from the server with the client. But, if i connect to the roundcube webmail, i can send emails with the webmail interface. I'm using port 25 and 587

The error message in my android when i tried to setup port 587 (accept all ceritifcate) is cannot safely connect to server

error message in Thunderbird
Sending of the message failed.
The message could not be sent using Outgoing server (SMTP) for an unknown reason. Please verify that your Outgoing server (SMTP) settings are correct and try again.

Error message in rainloop
stream_socket_client(): SSL operation failed with code 1. OpenSSL Error messages: error:140770FC:SSL routines:SSL23_GET_SERVER_HELLO:unknown protocol

===============
UPDATE
===============
Port 25 is working now

how i solved it:
- in rainloop admin domain setting - check on the "use authentication"
- in thunderbird i changed the port to 25 and authentication type is "password, transmit insecurely"

But I still cannot get it working on port 587 Is it Certificate SSL Problem? 

Can you tell me how to fix this ? can anyone give a little advice ?

thanks in advance