After the migration, we should send users an email informing them that the migration happened and listing issues that have been created by them, assigned to them, and followed by them.

In order to do this, we should write a tool that goes through all the users, gathers the data, formats the messages, and sends them to the users. This summary could be made available on bpo too, and the email could contain a link in addition to or instead of the lists (these summaries are already available in the sidebar for logged-in users).

This works well for occasional contributors that are involved in less than one or two dozens of issues, since they can go through them, review them, and resubscribe manually (if they are still interested). However it doesn't scale too well for people that follow hundreds of issues, and having a way to resubscribe users to issues that they were following would be better (see #5 under "nosy list").

Even if we find a way to preserve the nosy list during the migration, the email would still be useful because:

• it will inform every bpo member that the migration happened (unless we want to limit the recipients to people that have been active recently)
• it will give them a chance to review and possible update their old issues
• it will provide a quick way to find their issues on GH, even if they lost access to bpo

The exact wording and format of the email still needs to be determined:

• it should include a paragraph or two explaining that the issues have been migrated.
• it should include 3 lists: created by you, assigned to you, followed by you. These matches the 3 summaries available in the sidebar of bpo. Links to the summaries and total number of issues in each list could also be included.
• it should include the issue titles, links to the GH issues, and possibly links to the corresponding bpo issues too (not essential since they are already linked at the top of the GH issues).
• it should encourage the users to review and possibly close old issues if they are no longer relevant.
• it could list all issues, or be limited to a maximum amount in case someone is following hundreds or thousands of issues.
• it could be sorted by different fields depending on the list, or just sorted by date/descending
• it could be limited to issues that are still open, or also include closed issues (possibly in separate lists).
• it could include additional metadata (possibly similar to the weekly report).

Given the number of users, we might have to take some care in sending out a large number of emails at once, since it might be seen as spam.