Mail Suddenly Will Not Connect

Question

Mail has worked perfectly since buying this computer a year ago. I sync with three mail accounts: an exchange server at work, yahoo mail (POP), and my mobile.me account. Suddenly, mail will not connect with any of them, even though I am connected to the internet.
This problem coincides with my receiving the dreaded "self-assigned IP address" error message on airport. This prompted me to reset my airport express base station, to zap my PRam, and restart my computer a couple of time. I am now back online, but mail won't connect. I just get spinning wheels next to all three accounts, and the little hazard/exclamation point sign.
I tried connecting to the internet directly with an ethernet cable, and that did not help either. All the account settings in mail appear unchanged. All my downloaded messages are there. But I cannot connect. I have mail in the queue waiting to be sent, so I can't connect either to send or receive.
Suggestions?

Answer 1

Could be a DNS issue, since you had to reset the basestation, if the DNS settings where being provided by DHCP.
See if you can do the following. (Ping your email servers)
Go into the terminal (Applications/Utilities/Terminal
at the prompt type
ping (Work email servers address)
you could see the following.
PING pop-sbc.mail.fy4.b.yahoo.com (216.252.120.29): 56 data bytes
64 bytes from 216.252.120.29: icmp_seq=0 ttl=57 time=23.697 ms
64 bytes from 216.252.120.29: icmp_seq=1 ttl=57 time=23.364 ms
64 bytes from 216.252.120.29: icmp_seq=2 ttl=57 time=23.788 ms
64 bytes from 216.252.120.29: icmp_seq=3 ttl=57 time=24.701 ms
64 bytes from 216.252.120.29: icmp_seq=4 ttl=57 time=23.382 ms
If the address resolves correctly
Ping the Yahoo servers address, again you should see something similar to the above, if DNS is resolving the hostnames.
Not sure about mobile.me
If DNS is not working you will see something like this.
brent-hendrickss-mac-pro:~ hendrb$ ping [email protected]
ping: cannot resolve [email protected]: Unknown host
If it pings back correctly, do the following to make sure you can actually get out through the correct ports.
1) Verify for each account, which port the server is using.
In Mail. Go to Mail / preferences / Accounts (Click on the advanced tab)
If you are using SSL the port # will be 995, if your are not using SSL the port # will be 110, the port # will most likely be different for the works Exchange server.
2) go back to the terminal and see if you can telnet to the POP server.
telnet pop.att.yahoo.com 995
If it is successfully you should see something like this
rying 216.252.120.29...
Connected to pop-sbc.mail.fy4.b.yahoo.com.
Escape character is '^]'.
type BYE and enter to disconnect.
If it does not work and you get something like this
[email protected]: nodename nor servname provided, or not known
You might want to make sure you are allowing those ports in your firewall settings.
Hope that helps,
Brent