Large Attachments Won't Send

I have recently started parallel running emClient with Outlook in a view to moving over to it.  All is generally good but when I send large attachments it fails with the error

"[SMTP] An attempt to connect to failed. This could be caused by temporary server unavailability or incorrect settings. Do you want to check the settings?"

Now if I send small files, it works fine, if I send a larger file can take a while to throw the error or it can happen straight away. If I send the same file using Outlook it goes just fine. I have compared the server settings with Outlook and they are identical to those in emClient. I would very much appreciate some advice.

Same problem exactly. sorry to see you didn’t get a reply… we’re evaluating em client on 4 work stations and it’s better than Outlook in every way but this is a deal breaker… 

Hello everybody,

Could we please ask what e-mail service are you using? The Exchange Web Services protocol has built in limit for request length so maybe the larger messages that you send hit the limit. Please try to adjust the server settings and make sure that the setting “httpRuntime maxRequestLength” is set to 20000 for 20MB limit or to 50000 to 50MB limit.
If this helped, it would also explain why there were no issues in Outlook, because they use a different protocol for communicating with the server.

Let us know how it went.

Thank you,