Outgoing Mail Servers

Your phone will try outgoing mail servers based on what you have configured in Settings -> Mail, Contacts, Calendars -> <your account name> -> Account -> SMTP. You can see on that screen the primary server, meaning the one it will always try first, then below, you can see (or add) additional ones that can be turned on or off. Unfortunately, as of now, there is no way to tell your phone to use a specific server based on your current location. If one fails because you aren't at work, then it will move to the next one to get the message out.

Did that make sense? Hope it helped.

I have a similar problem. I have a primary smtp for home wifi and use cell phone provider's smtp in the car etc. I tried disable primary because it takes the iphone 5 minutes plus to try the other smtp address. This happens even when the primary is turned off. Also while this is going on the system is adding additional other smtp accounts for the cell phone smtp as duplicates even though there is an original one present. Is this a bug?

I'd have a chat with your e-mail provider, because unless you are using a specific work account with unique security, a standard server setup should work from your home to Starbucks to a faraway airport's wifi.

Ensure it is using port 587 or 465 with SSL enabled.

Your phone will make available every SMTP server configured on your device (usually at least one for each configured e-mail account) within the settings for every e-mail account. Meaning, your Gmail account will give the option to turn on a Hotmail account SMTP server (if you have Hotmail also set up on your phone).

In normal situations, one SMTP server is sufficient for all places.

Found a fix to my problem after consulting with Rogers and Cogeco which may be of interest to Rogers Iphone users using and configuring Cogeco email address on Rogers cell network. There is definately a clitch in Apple programing in configuring cogeco accounts and maybe other pop servers. The problem is outgoing email is polling primary smpt (set up for cogeco during installation) when roaming on the rogers network while away from local wifi network. Though Rogers Iphones have smtp.rogerswirelessdata.com listed in the alternate smtp settings, the software will continue to poll the primary even if turned off for 5 to 8 minutes before switchinhg to rogers server to send the email. Rogers smtp must be enabled as an alternate server as well. The work around to avoid this is to enter rogers smpt server in the primary account (instead of default Cogeco smtp. You have to patiently verify 3 times before the system accepts at the "continue without ssl prompts" for the setting to stick. Thereafter you should see your cogeco account using smtp.rogerswirelessdata.com as the outgoing server. If this does not solve the problem turn off primary server and turn on the rogers alternate server below. My outgoing email was now working within a few seconds. Of course you cannot use your wifi network to send email from your phone but it will work from the Rogers network for your cogeco account when on the road trying to reply to incoming emails. All this is unnecessary for gmail accounts which works ok on the Iphone (at least for me). Rogers and Cogeco Technical support are now aware of this and are in the process of working with Apple to solve this glitch. Also verify the port settings are correct as Apple sometimes assigns the wrong port number during setup. The correct outgoing smpt port number is 25 but you can only change it after the configuration process completes.