Yesterday I learned that some ESPs don’t support the reply to: address. I asked around to discover which ESPs did. Here’s what I learned.
ESPs that support reply-to:
Twilio / SendGrid
Thanks to all the colleagues who answered my question.
For the record we (MailUp) support the reply-to as well.
I would expect that ESPs that do not support it are the vast minority (provided they are more than one)
Twilio SendGrid also supports setting a custom reply-to address.
You can add Dolist and NP6 on the list.
Both do not make this a mandatory field, but they do support (and promote) its use.
I agree with Alberto that most ESPs are supporting this. It makes a lot of sense to do so when you consider that most ESPs now require thier clients to use a subdomain to send. The reply to field allows the client to specify a usable adress on its own infrastructure without requiring to set up mail redirections or such from the mailfrom adress (and all the issues that go with mail forwarding).
GetResponse also supports a custom reply-to address.