Issues with SMPT server

I am setting up SMPT with mailgun and am getting this error:
The selected mail encryption is invalid.

My encryption method is TLS. How do I fix this error?

RiversideRocks TLS typically uses port 587 to send mail. If you're using 465 for example, that's SSL and could be where the disconnect is

I tried using port 456 with SSL, still no luck.

RiversideRocks can you send a screenshot ?

The value should be lowercase but that doesn't have a functional difference. If it sends emails without erroring there's nothing to worry about.

I set it to lowercase and that did the trick. Thanks!

I find error on this. Please help me

kishor please share as much detail as you can about your issue.

What error message do you see? Check Flarum log file and browser console if needed.

What are your email settings? (ideally share a screenshot of copy of all the settings, except password)

Did you migrate from an older Flarum version?