The iPhone is one of the best options for corporate users that need mobile email. However, people that perform several roles within one company usually need to send email using one of several “alias” addresses, such as sales@company.com and fred@company.com, depending on the role they are working at that time.

Unfortunately the iPhone makes sending such emails from one account very difficult. If that account is hosted on a Microsoft Exchange system, it is almost impossible.

The best workaround to this problem we have found is to enable SMTP mail support on the Exchange server as well as the normal ActiveSync access. As all mail servers provide some sort of SMTP support, this might sound a little confusing, so we’ll go over it in detail.

A basic Exchange setup providing email to an office based staff would connect people to Exchange using Outlook and Microsoft’s MAPI protocol. For users to receive mail from other mail systems located elsewhere on the Internet, the Exchange server would also support anonymous SMTP connections. However, this type of SMTP connection would reject mail that was not addressed to one of the company’s Exchange mailboxes. This setup works very well when all users are connected via the company LAN, but does not work if users need to send and receive mail while working outside the company office.

To support those “mobile” users, the Exchange administrator would need to enable ActiveSync protocol support on the server and company firewall. This would allow mobile users to send and receive email, for example, using Outlook running on a laptop, provided the laptop had a working connection to the Internet.

Apple’s iPhone 3G, 3GS, 4, 4S and iPhone 5 all work very well with Microsoft Exchange and ActiveSync. In particular, they provide push notification when an email arrives, and they provide access to corporate calendars and address books. However, an iPhone Exchange account does not support sending mail using an alias email address. Exchange administrators call this setup “Send As”, because of the naming conventions used to configure an Exchange server, and it is an extremely common requirement.

To work around this limitation, an Exchange administrator must configure the server to allow users to connect via POP and SMTP. Then, iPhone users requiring Send As access must have their iPhone setup with an additional email account that can access their Exchange account using those protocols. In our case we setup the additional iPhone account as a POP account and use a dummy account for the POP access on the server. This way, the user does not see two copies of each email in their iPhone inbox – one from the ActiveSync account and the other from the POP account.

For our tests we created an Exchange mailbox called Dummy Room, and enabled POP access for this account.

We then created the second mail account on the iPhone as a POP mail account, and set the Email address in the iPhone “POP Account Information” panel to be the alias email address.

For the “Incoming mail server” details, we use the Dummy Room account credentials and our Exchange server’s POP access address. Given that no external email is routed to this mailbox, Dummy Room’s inbox will always be empty.

Finally, for the iPhone “Outgoing Mail Server” panel, we used our user’s normal Exchange account details. Mail sent from the iPhone using this account will appear to come from the alias address rather than the normal Exchange account reply address.

You only need setup one extra account on the iPhone regardless of how many aliases the person needs. Setup multiple aliases in one iPhone email account using a comma separated list of email addresses in the account “Address” field. As the iPhone does not allow you to type a comma in this field you must use the Note app to create the list, then cut and paste it into the Address field.

Clearly this is something of a crude work-around, and it would be better if Apple would fix the problem by adding support for Exchange Send As in the iPhone mail app. Currently this is the best solution to the problem that we are aware of. If you have any better ideas, please let us know!

Thanks to Jim for pointing out that Sent email ends up in the iPhone Sent folder, rather than in the normal Exchange account Sent folder.