More than SMTP hosting, but I use a VPS for multiple online services, including SMTP. SMTP in particular is handled by postfix, OpenDKIM, policyd-spf. Its incoming mail part is additionally supported by uacme with knot, nftables, fail2ban, but sounds like you are not in need of that. 1 GB of main memory, 10 GB of disk space, and a bit of CPU is a comfortable (overkill, even) system to run a variety of services with a few users and without particularly bloated software, and I think it normally costs less than $5/month (or even under $1/month with occasional promotional plans), with plenty of hosting providers to choose from.<p>Edit: my current setup is documented [0], and the older (slightly different) one is linked from it.<p>[0] <a href="https://steady.mooo.com/~defanor/notes/simpler-server-setup.html" rel="nofollow">https://steady.mooo.com/~defanor/notes/simpler-server-setup....</a>