I do not use that SMTP server for my email, but hopefully I can help you find an answer or at least w workaround for your problem. It is not uncommon for a traceroute to not work at all hops of the trace. If you do a dig or an nslookup what do you get as an answer for that hostname? Here are my results:
;; ANSWER SECTION:
smtp.bizmail.yahoo.com. 300 IN CNAME smtp.bizmail.mail.fy4.b.yahoo.com.
smtp.bizmail.mail.fy4.b.yahoo.com. 300 IN CNAME any-smtp.bizmail.mail.fy4.b.yahoo.com.
any-smtp.bizmail.mail.fy4.b.yahoo.com. 300 IN A 188.8.131.52
There are a lot of CNAME's in there. To temporarially rule out the DNS what happens if you use the IP address 184.108.40.206 as your outgoing smtp mail server setting in your email program? As of right now that appears to be a valid and working mail server for the name that you are trying to use.
Connected to smtp1-f.biz.mail.vip.re2.yahoo.com (220.127.116.11).
Escape character is '^]'.
220 smtp102.biz.mail.re2.yahoo.com ESMTP
Did Yahoo Support say that the DNS answer you were getting was old an not valid?
Another common problem is anti-virus software on your computer scanning and blocking outgoing emails. It may also be scanning and working correctly but your mail program is timing out before the virus scan has finished. Did you make any changes or download a new anti-virus program around two weeks ago? If you are using free software, my preference is Avast! If you are never able to send email you should also check the firewall settings and blocked programs list if you have a firewall on your computer.
I hope that helps, and
to Email Questions! -Raymond