If you don’t know what YouMail is, I suggest you read up on it. In short YouMail is a free service that replaces your carriers voicemail system. It lets you create custom greetings per caller/contact, and much more. One of the main features is the ability to receive your voicemails as email attachments.
The problem with using YouMail with your BlackBerry in the past was that you could only receive voicemails in WAV format. This is because with OS 4.2 you could not open MP3 files as email attachments. I confirmed this by calling RIM. It seemed strange to me that I could play MP3 files in the media player but not open them as attachments. In OS 4.5 that limitation is gone. You can now receive MP3 files which are much smaller in size than the original WAV files. This lets you listen to your voicemails faster.
To receive MP3 attachments you must change your YouMail settings as follows:
As an FYI, YouMail requires you set voicemails to be forwarded to YouMail. Your carrier may or may not include these call forwarding minutes with your monthly plan, as T-Mobile does. Consult your physician carrier to see if YouMail is right for you.