Locale E-Mail sink

I do have multiple mail accounts (personal, university, work, …). Currently I'm connecting from every device (notebook, smart phone, tablet,…) to each of them via IMAP . Setting up multiple IMAP and SMTP accounts on each device sucks, especially if you're changing the mail client quite often like me.

So I'd like to host some thing like a "locale e-mail sink" on my Raspberry Pi. I'd like to fetch all the mails from the multiple mail accounts from the Raspberry Pi (with offlineimap), and then make them available for my devices through one IMAP server. As a result, I do only have to configure the Raspberry Pi IMAP server on each device. The only remaining question is, if it is possible to set up an SMTP server on the Raspberry Pi, that justs forwards the mail to the real SMTP servers, in a way that I only have to configure one SMTP server on each device.

Can you recommend me an (easy to configure) SMTP Server that provides this? I haven't found yet anyone or just not the right pages in the documentation about it.