I, like most you, upgraded to ML the other day, but since yesterday I haven't been able to send mails through o2's smtp server (It's possible the problem persisted since before yesterday - I hadn't tried sending mails in a while).
The message I get is as follows: Cannot send message using the server smtp.o2.co.uk
The SMTP connection to the server "smtp.o2.co.uk" failed
First of all, I thought that it was o2's servers, but this has been disproved, because I can send mail from my iPad (latest WiFi version) without issues, either from my own WLAN, or when connecting via BT OpenZone at work.
Here's my diagnostic attempts so far:
• Edited mail settings and re-entered all details from a known good source (I have a plain text file that has all the details therein and used this as a template) - Problem still persists
• Created a new user account via System Preferences > Users and Groups and set mail up from there with the above - Problem still persists
• Ran Keychain first aid on the original User account in case of corrupt data in the keychain - No problems found with the keychain
I have spoken with Apple, but unfortunately, the call got cut off cos the call centre closed, but up to that point, the techie had been helpful, suggesting option 2, above.
So far, I'm at a total loss as to what my next step is in the troubleshooting process, or even if there is a next step
Any thoughts or advice would be appreciated