SMTP sometimes could connected, sometimes could not connect and repose -1

[Harry Huang]

After I finsihed SMTP configuration, and try to "Test Connection".

It's two status, one is connected, another is could not connect and repose -1 .

But, the configuration is the same!

Does any ideas?

[Dirk Ronsmans]

Hi @Harry Huang ,

I'm wondering about a few items:

• what type of mail server are you using? (local/cloud)
• are you using a specific mail server or is the hostname a load balanced fqdn?

If you are using a loadbalanced hostname it could be that some of the ip's in the list are just not accessible. Same for Cloud to be honest, if you have whitelisted some ip's/hostnames it could be that not all are yet in the list.

[Harry Huang]

I use outlook exchange server, so is it cloud? I am not very sure about this.
And we don't use load balance.

[Dirk Ronsmans]

Well Exchange could be on premise or Cloud (Office365) and it does matter for troubleshooting.

Personally I would take this up with your exchange/email administrator first to get all the details and maybe have them troubleshoot the connection as well.

Otherwise it's really just a stab in the dark as to what could be wrong I'm afraid.