Email marketing links present a specific version of the old-links problem: campaigns already sent and sitting in inboxes can't be edited retroactively, and will always contain whatever URLs were live at send time.
What actually needs doing
- Confirm your server-level redirect handles old http:// links correctly — this is what makes already-sent campaigns keep working, without needing to touch the emails themselves.
- Update the default sending domain/link settings in your email platform going forward so new campaigns use https:// links directly, avoiding the extra redirect hop for future sends.
- Check email templates (not just individual campaign content) for hardcoded logo or asset URLs using http://, since these can trigger "images blocked" warnings in some email clients even if the link itself redirects fine.
As long as the redirect stays permanently in place, there's no urgency around old campaigns specifically — they'll continue to work indefinitely.
Why old campaigns don't need to be individually fixed
As long as your server-level redirect remains permanently in place, links in already-sent email campaigns continue working correctly indefinitely — there's no need or ability to retroactively edit an email that's already been delivered to inboxes, and the redirect handles this automatically.
What to update going forward versus what the redirect already handles
Going forward, updating your email platform's default sending domain and link settings to generate https:// links directly avoids the small extra redirect hop for all future campaigns, even though relying on the redirect would technically still work for anything the platform continues generating with the old protocol.
What to check in your email service provider's domain authentication settings
While unrelated to the HTTPS redirect itself, a migration is a reasonable moment to also confirm your email service provider's domain authentication (SPF, DKIM) is still correctly configured, since email deliverability issues are sometimes mistakenly attributed to an unrelated HTTPS change happening around the same time.
What click-tracking redirect domains mean for this specific consideration
Many email marketing platforms route links through their own tracking redirect domain before forwarding to your actual destination URL — confirming your platform's tracking redirect itself correctly forwards to your https:// destination is worth checking specifically, since this is a layer separate from your own site's configuration.
How to audit past campaign templates for any hardcoded assumptions
Reviewing your email platform's saved templates, not just individual past campaigns, for hardcoded http:// image or link references ensures future campaigns built from those templates don't inadvertently reintroduce outdated protocol references.
Why transactional emails deserve the same review as marketing campaigns
Order confirmations, password reset emails, and other transactional messages are often generated by separate application code from marketing campaigns, meaning they need their own independent check for hardcoded http:// links rather than assuming a marketing platform review also covers them.
A closing thought on treating this as a minor, low-priority migration item
Given that the server-level redirect handles old campaign links automatically and indefinitely, this is genuinely one of the lower-priority items on a migration checklist — worth addressing for future campaigns' sake, but not something requiring urgent attention during the core migration itself.
What A/B testing considerations apply if you're mid-test during a migration
Pausing or completing an active A/B test before migration, rather than running it through a protocol change, avoids introducing a confounding variable into your test results — a migration mid-test makes it difficult to attribute any change in test performance to the test itself versus the concurrent infrastructure change.
How to handle links in automated drip campaigns specifically
Automated drip or nurture campaigns with a long enrollment window benefit from the same redirect-based continuity as any other email links — existing enrolled contacts continue receiving working links via the redirect, while updating the campaign's own templates ensures newly enrolled contacts receive https:// links directly going forward.