Thank you for your post!
I tested this out with:
Server - smtp.mail.yahoo.com
Port - 465
Connection Encryption - SSL
Authentication - Plain Password
UserName - XXX@yahoo.com
Password - XXXX
It didn't initially work. I received an email complaining about an insecure sign in and found the following resolved this:
"If you still want to use an app that uses less secure sign in, go to https://login.yahoo.com/account/security#other-apps and turn on "Allow apps that use less secure sign in". This is not recommended and may leave your account more vulnerable to compromise. To learn more, please visit our help page: https://help.yahoo.com/kb/account/SLN27791.html "
After changing that settings I was able to send out without error.
I'm also going to move this thread from the FileMaker Community Feedback Space (which is specifically for input on the Community itself) to the Discussions Space where you should receive more views and potentially more feedback on this topic!
I selected the less secure option.
Try setting the username to not include the "@yahoo.com". I haven't done STMP email via Yahoo in a few years, but my notes from back then showed the username being entered by itself.
If you're sure you can email Yahoo securely from, say, a regular email client, what I would do in this situation is EXTERNALIZE the email to a mini web service that uses the extremely powerful, but easy-to-use JavaMail API.
I've done this several times with FileMaker. The person using the FileMaker application has no idea that email is handled any differently as all they do is click a button (or tie the email to an event or whatever) to send the email.
Assuming you're using the same settings, and can do secure emails externally but not using FileMaker, then there is a problem with FileMaker, not Yahoo!
Personally, with all the published data hacks, I avoid Yahoo!, but that's not always possible.
HOPE THIS HELPS.