From the main project page, it mentions it has typical alias support:
<i>>Email aliases, mailing lists, subaddressing and catch-all addresses support.</i><p>Another feature that would be nice to have built-in is <i>masked hide-my-email aliases</i> for privacy like the cloaked email services from iCloud, FastMail, SimpleLogin, Cloudflare email routing, etc.[1]<p>For now, I use the typical aliases addresses in Dovecot but it doesn't hide the real email when replying. Also, creating new aliases in Dovecot-based email systems is very tedious and cumbersome because you have to go through the cPanel interface to create them. (Some suggest using the "catchall" feature to avoid the need to manually create new aliases but that advice is not workable when spam robots constantly send emails to new random addresses in your domain.) The cPanel/Dovecot aliases also don't have any metadata so you can add details on what the alias is for and when it was created.<p>[1] masked email services examples<p><a href="https://support.apple.com/en-us/105078" rel="nofollow">https://support.apple.com/en-us/105078</a><p><a href="https://www.fastmail.help/hc/en-us/articles/4406536368911-Masked-Email" rel="nofollow">https://www.fastmail.help/hc/en-us/articles/4406536368911-Ma...</a><p><a href="https://simplelogin.io/" rel="nofollow">https://simplelogin.io/</a><p><a href="https://blog.cloudflare.com/introducing-email-routing" rel="nofollow">https://blog.cloudflare.com/introducing-email-routing</a><p>EDIT ADD to reply : <i>>On Stalwart you can implement masked e-mail using address rewriting</i><p>Stalwart's feature of "Sieve scripts" for custom rewriting/filtering is interesting but it's not UI friendly for endusers to create new masked email addresses (and also later delete them). There's also no user-defined metadata. It's also not clear if Sieve scripts can run on <i>outgoing mail</i> rather than just incoming mail. Example of how UI workflow in Apple's Hide My Email is simpler than Stalwart Sieve scripting: <a href="https://www.youtube.com/watch?v=oJRrkJy0vUk&t=34s" rel="nofollow">https://www.youtube.com/watch?v=oJRrkJy0vUk&t=34s</a>