Mail fails to connect to smtp servers after 10.9.3 update

Question

Wiped hard drive and installed 10.9 plus 10.9.3 combo updater.
90% of my email accounts cannot connect to their smtp servers.
Created a new user account and setup Mail with an account with the same result.

Answer 1

Confirmed.
At my University, I have a locally produced .mobileconfig file that is used to set up network, mail and all other access on a new Mac / Macbook. Further, the University uses a self-signed certificate to authenticate all connections.
Up until 10.9.2, Mail worked normally as it should.
After 10.9.3, Mail works for the imap server (and I can receive email fine) but sending email via the smtp server fails at all times except the ones noted below (read on). Connection doctor says that smtp server rejected authentication and advises me to recheck my username and password (needless to add - they are correct).
smtp connections work if:
1. I delete all Mail accounts.
2. Use the University-supplied .mobileconfig file to recreate all accounts (LDAP, mail, wifi, etc.).
If however, I close my macbook to sleep it, or change network settings (go from proxied to non-proxied mode, or vice versa - which was never a problem until now), smtp stops working.
Upshot - smtp works only if I delete my accounts everytime I wake up the macbook and redo steps 1 and 2 above. I have taken to saving contents of the outbox to the drafts folder, and then logging in through the webmail interface to actually send the email.
This is nuts.
Apple's engineers need their heads examined if they think that rolling out an inadequately tested update is acceptable.