This computer

The companion is the part of Rowsend that sends your email, records unsubscribes and reads bounces. By default it runs inside Rowsend on your computer. That costs nothing and needs no setup. Choose where it runs in Settings → Companion → Where it runs.

	This computer	My server	Rowsend Cloud
Unsubscribe links	Reply to unsubscribe	Yes	Yes
One-click unsubscribe (Gmail, Yahoo)	No	Yes	Yes
Bounces from SES, Postmark, Mailgun	Yes	Yes	Yes
Bounces over SMTP	No	With a bounce domain	Yes
Hosted images and social icons	No	Yes	Yes
Sending with the computer off	No	With a master key, if you turn it on	If you turn it on
Cost	Free	Your server	Subscription

What works differently here

Recipients’ mail apps can’t reach your computer, so:

Unsubscribing is by reply. Emails say “Don’t want these emails? Reply to this message, or write to …, and we’ll remove you.” The unsubscribe header asks mail apps to send an email to your reply-to address. You read those replies and mark the contact unsubscribed yourself: open the contact on the Contacts page and click Unsubscribe. The send dialog asks you to confirm you’ll do this before each campaign.
No hosted images. Use image URLs from somewhere public instead of uploading. The Social block shows text links instead of icons.
No SMTP bounces. Use Amazon SES, Postmark or Mailgun, which report bounces through their APIs.
Scheduled campaigns need Rowsend open. The computer must be awake and Rowsend running at the scheduled time. A campaign more than an hour late goes back to being a draft rather than sending late.

Rowsend has to be running to send

This is true wherever the companion runs. Rowsend hands the companion your provider’s credentials only while it’s running, and the companion forgets them about 30 seconds after Rowsend stops refreshing them. If you quit Rowsend mid-send, the remaining emails wait and go out when you open it again. Only Rowsend Cloud or your own server can keep credentials and send with your computer off, and only if you turn that on.

For real unsubscribe links, run the companion on your own server or use Rowsend Cloud. Switching keeps all your projects, contacts and campaigns, since those live in Rowsend, not in the companion.

Switching companions

Switching keeps all your projects, contacts, campaigns and unsubscribes. Rowsend refuses to switch while a campaign is sending, is scheduled on the companion to send with your computer off, or went out in the last 24 hours and is still collecting bounces. When you switch away from your server or Rowsend Cloud, Rowsend first deletes any sending credentials it kept there.

Emails you’ve already sent keep using the old companion: their images load from it, and their unsubscribe links record there. So when mail went out through the old companion:

Rowsend keeps counting its unsubscribes for 30 days. It reads them every hour, and before every send, alongside the new companion’s. Settings → Companion lists each old companion with the date it stops, and Stop now ends it early, for example once you’ve shut a server down. If one can’t be reached for a day, Settings says so.
Keep your old server running for those 30 days. Unsubscribe links in mail sent from it only work while it’s up, and the law in most places expects them to work for at least 30 days after you send. Rowsend Cloud keeps your links working for you, but you can’t sign out of it until the 30 days are over.
Move your images. The switch offers to copy every image you’ve uploaded to the new companion, ticked by default. Drafts, templates, campaigns scheduled on your computer and your brand logo then use the copies; sent campaigns keep their original images, and a duplicate of one uses the copies. Images that don’t move keep their old address, and Settings shows how many with a Retry button. This computer can’t host images, so switching to it leaves them where they are.