I would not recommend using an Iridium phone directly with Mac OS X "Mail" application. I do recommend using GMN XGate as the go between.
Configure OS X Mac "Mail" application for use with XGate.
Note that XGate comes bundled with the Mozilla Thunderbird e-mail client which works out of the 'Box'. The following steps are only necessary if you prefer to use the Mac OS X "Mail" client instead of Thunderbird.
1. Run XGate
2. Go to preferences and click on the e-mail settings tab and confirm that the pop and smtp port numbers are set to the following POP3 Port #: 1100 and SMTP Port #: 2500. Click OK and then Exit and re-run XGate only if the POP and SMTP port numbers were changed from their default values.
3. Run the Mac "Mail" Application and select File->Add Account
4. Set the Account type to POP
5. Enter XGate or GMN for the description
6. Enter your Full Name
7. Enter your e-mail address (lsoltero@gmn-usa.com or some such thing).
8. Set the Incoming Mail Server to 127.0.0.1
9. Enter your GMN/XGate assigned username and password. (this must be the same as the username and password entered above when configuring XGate).
10. At this point you will get an error that states that the pop server is not responding. Dont worry and hit continue.
11. On the next screen leave the 'Use Secure Sockets Layer (SSL)' unchecked and set the Authentication to Password (the default)
12. Enter 127.0.0.1 for the outgoing mail server. The 'Use Authentication' should be left unchecked. You will receive an SMTP server not responding error when you hit continue. This is expected. Hit continue.
13. On the next screen leave 'Outgoing Mail Security' unchecked.
14. Finish the wizard.
15. Next go to Mail->Preferences. If you have more than one account listed then move them around so that the XGate account is at the top. You will want to 'disable' all accounts except your XGate account. This will prevent the "Mail" application from trying to check non XGate (i.e. non compressed ) accounts when using the mail program.
16. Now click on the XGate account and under the Account information tab click on the "Server Settings...†button. Set the server port to 2500 (the value entered in the previous section for SMTP port number. Hit OK.
17. Next click on the "Advanced†tab. Set the POP port number to 1100 (the value entered above for the POP port number). Also check 'Remove copy from server after retrieving a message:'
18. Finally click on Signatures and then on the XGate account and enter a signatures that will let your users know that you are using a satellite phone to send you e-mail and that care should be taken with attachments and other content.
19. Back in XGate execute "Tools->Launch Default E-Mail Client" to bind the E-Mail toolbar icon to Mac Mail.
Test your e-mail settings by composing and sending an e-mail in the Mac OS X "Mail" application. You should see the flag on the XGate icon on the launch bar start to go up and down. This means that you have an e-mail message ready to be sent out.
Bring up XGate and push the "Start" button to send your e-mail.
http://www.globalmarinenet.net/email.htm