Element
element.io
End-to-end encrypted group chat in a browser tab, on the open Matrix network
Free account
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Send, receive, alias, authenticate and test email.
element.io
End-to-end encrypted group chat in a browser tab, on the open Matrix network
formspree.io
Gives a static site's contact form somewhere to POST that emails you the answers
toolbox.googleapps.com
Paste raw email headers and see every hop, the delay at each, and the auth results
mail-tester.com
Send one email to the address it gives you and get a spam score out of ten
mailerlite.com
Sends a newsletter to a small list on a free tier that does not expire
mailinator.com
Any address at mailinator.com already has an inbox you can read without signing up
mailtrap.io
Catches the emails your app sends in a fake inbox so no real person gets them
mxtoolbox.com
Looks up MX, SPF, DKIM and DMARC records and names the one that is wrong
proton.me
Encrypted mailbox where the provider cannot read the contents of your messages
simplelogin.io
Gives every service its own email alias so you can cut one off without moving
zerobounce.net
Checks a mailing list for dead, catch-all and spam-trap addresses before you send
zoho.com
Turns a shared support@ address into an assignable queue for up to three people
By task
Archive
Kept on record so an old bookmark still leads to an answer. Each one names the site that does the job now.
Questions
There is no single answer, which is why this page lists 12 of them with their limits stated. If you want to avoid signing up entirely, 1 of these work with no account at all.
Every site in this category sends your input to its own server to do the work. That is fine for public material; for anything containing personal data, check the on-device collection instead.
Some already have. 2 entries in this category has been retired and moved to the Archive with a working successor, so an old bookmark still leads somewhere useful.