Cannot SEND mail - connection to outgoing server failed.

You are using the settings synced from home, but are you connected at home? Many ISPs only allow access to their smtp servers over their own network. Others require different settings when connecting from outside (which you're doing when you're on 3G/EDGE). Another option is to use AT&T's outgoing mail server to send. You can enable that in Settings > Mail, Contacts, Calendar > tap insight account > Outgoing Mail Server/SMTP > set AT&T SMTP server to ON. That way, the AT&T server will be used away from home (as long as you're connected to 3G/EDGE/GPRS - if you're connected to another Wi-Fi network it won't work) and your ISPs server will be used at home.

dzash2000 wrote:
Hi - I have not been able to send email even if I Reply to a message I receive. I have the settings sync'd from home (Comcast) and the settings I was given by the hosting service where my website and the email address I use is. Neither work and I suspect the iPhone's capability. All the settings have been checked multiple times. It's been 4 days.

"The connection to the outgoing server "smtp.comcast.net" failed".
"The connection to the outgoing server "smtpout.secureserver.net" failed".

it has nothing to do with the iphone's capability. it's failing because you are trying to send mail through comcast's outgoing mail server when you aren't on comcast's network. you can send mail your comcast mail fine from your home computer because your home computer is getting it's internet service from comcast and the mail is set up specifically for that, the mail is being sent through their port and outgoing mail server. when you leave your home you are no longer have comcast's internet service and is having issues connecting to their mail server from at&t's network.

instead of syncing your mail settings try setting up the comcast email account manually using this link as a reference: http://www.apple.com/support/iphone/mailhelper/

I've also occasionally received errors like:
"the recipient's address cannot be found" - but I'm replying! There couldn't be a typo!
"the sender's address is incorrect" (or something like that).

yes there could be a typo. the recipients address comes from the reply-to information that the recipient entered in. whatever they enter in their reply-to field is the address that will be used when people reply to their message, they could easily have a typo on their end.

Could these be related to the "outgoing server" error or is it a totally different problem?

different problem. the outgoing server and a typo in an email address are two different thing.

I also have a yahoo account with different settings that totally works - go figure.

that's because you are using the outgoing mail server for yahoo which can work on whatever network you are on (your home wifi, or at&t).

What else can I try? Who should I call?

the problem is with comcast, call them.

try setting up the email manually following the steps at the link i provided above instead of syncing the email account settings.