Cannot Send Mail Sender Address Invalid

If it still applies Cox were known for blocking Port 25 which email uses and people only had access to webmail.

Have you had other computers accessing mail other than through webmail or have you always used webmail before the iPad?

I have the same problem with POP accounts (@mac account works well). Not in Cox network. All works well on both Macbook and iPhone but not iPad. Called apple support but after long discussions I got "disconnected" with no answer. Any fixes?

mine fixed by doing what aahmie suggested AND adding my username and password in the "outgoing mail server" info, even though it says "optional" (same username and pw that's listed in my "incoming mail server"). Works great now.

You can, for a around $15/yr., send up to 150 emails a day over wifi using an independent outbound SMTP server ... works GREAT for Cox with my iPad, iPhone and laptop. I use a service from dyndns.com One account will service multiple email addresses too.

Very easy to set up the devices.

I just encountered the same problem today on my iPad.
I have a google app gmail account on my iPad (godady domain name email), I was able to receive and send mails through this account until today.. Now I can only receive mail, but can't send any more, the error message says "sender address invalid".
The mail set up on my iPad is the same as my iPhone mail set up, I have no problem on my iPhone gmail app account. What has changed suddenly? I hate google, free mail, I get what I paid for.
Any suggestion? Any fix? Or I should just give up gmail and stick with MobileMe..

Well, after posting my previous message, I decided to delete the gmail account on my iPad and then add it back. This seems to have solved the problem for now. See how long it will last before the problem shows up again.

I have been getting the some of the same issues and some others. I have 2 pop accounts one is giving me no errors but i get a email then it disappears right away out of the in box the other I can never log in the mail account. What's more weird is that when I originally setup the iPad I did a restore from a iPhone backup and both mailboxes worked fine. But now I had to set it up as a new device to fix some of the apps crashing issues!

Husband just opened his new iPad 3G and is having the same issues 'Cannot Send Mail Sender Address in Invalid'... receiving fine but not sending

Some specs

He has a godaddy email account
We are on ATT wireless at home

Please help... there is liable to be an iPad travesty here soon :-/

I was having the same issues described here. My imap accounts were working fine. The pop3 accounts would receive mail but not send. Just got off the phone with Apple support. They walked me through a fix for my problem. Here is what we did. Went to Settings > Mail, Contacts, Calendars and selected one of my pop3 accounts. Scrolled down and tapped on the SMTP button. When the new window opened tapped on my primary server. Another screen opened. The Use SSL was selected. I turned it off. Then clicked Done.

Turning off SSL worked for getting my email up and running.

I'm having the same problem. Everything works fine in Mail on my Mail, iPhone4, and initially the iPad. Mail settings update automatically through MobileMe. But now, with no software updates or changes, the iPad won't send. The iPad Primary Account STMP is ameritech.net (AT&T) and I can't change it to .me nor get a password into in. "Can't be modified because it is the primary server"! Huh?

So good to see you have the same problem. iPad mac.com mail worked before, but today before the update, I started getting the message, sender address not valid on iPad. I updated and still not sending my email. I am trying now on upgraded iPhone and it will not send either.

It definately is the ipad. I cannot sign in to mac.com welcome on ipad through Safari. It brings up the set up page on Safari.

www.me.com/ipad_welcome/en/

I have been using my ipad for email since I got it. My MacBook Pro is fine, on https://www.me.com/mail/

A follow up to my earlier post: I seem to have solved my problem, but as someone else commented, I'm not completely sure how. The big issue was that on the iPad my .mac account thought I was using my ameritech.net (ATT) account as the SMTP "Primary" server and would not allow any changes, including entering a password. So I finally went back to the Mac and changed my .mac server settings there to use only the .mac SMTP server, waited for MobileMe to update the iPad, then was able to change things. (The iPhone4 had not had any of these sending problems.) But I then had to go through each account on both devices and re-enter passwords. Part of this is that Ameritech (ATT) wanted every account "verified". Some would revert to the previous state, but I finally got them all the correct way and things seem to be working.
What I still don't understand is why it went bonkers in the first place. When I got the iPad, everything worked fine, then suddenly, with no software changes, this craziness started!? Oh, well. Have since run the iPad update and things are still working.

I'm having the same trouble with outgoing mail. I've spent hours trying to get it to work with no sucess. I think it's the i-Pad and not me judging by the posts. I'm reading corrections that seem to be contradictory to each other yet still work, or don't.

My question, does anyone think Apple is aware of the problem? Does anyone think Aplle has staff checking these forums. I would If I was Apple.

Cheers