Dear Maintainer, I think that msmtp-mta and dma packages need to be co-installable. That is the rationale: - dma is a simple mail "server" that does not have a daemon, but works well for send the mails to local users, and to remote ones by SMTP. - Dma works well byself, without a daemon. But in some cases a daemon is neded to talk with some programs that isn't working without the daemon (in my case it is monit). - msmtp-mta is providing the msmtpd daemon, that is capable to talk with msmtp but TOO with any other mail "server" that does not have a daemon. For this msmtpd use the --command option. - But msmtp-mta is not coinstallable with dma. I try it in Debian Stable and this is the result: $ sudo apt install msmtp-mta Installing: msmtp-mta Installing dependencies: gsasl-common libgsasl18 libgssglue1 libntlm0 msmtp REMOVING: dma I think it is because msmtp-mta ships the sendmail command, that is too in the dma package. If it is the cause, this bug report may be the right one, and mine a duplicate: https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=969198 So, maybe we need to change the msmtp-mta package with the alternatives mechanism, made another package that be coinstallable with mda, or another solution... For complete this report, I made it and is working. This is the howto: I now have two, msmtp-mta and dma packages conistalled and running, and msmtpd is talking with dma, and sending the monit mails from it. I need it for have all mails be mailed by smtp AND saved on a local mailbox for security. For this I'm using the /etc/aliases mechanism that dma can use for send to local mailboxes (and no msmtp)... For this to happend, I made the following changes: - Download the msmtp-mta package, uncompress, remove all the "sendmail" "newaliases" related files, and remake the package with another name. Install it. - Change the msmtp-mta systemd unit to run with mda. Now my unit is as follow: [Unit] Description=msmtp daemon Documentation=man:msmtpd(1) [Service] User=root Group=root #User and group maybe is'nt needed, but I was madeing some probes with diferent users... Type=simple ExecStart=/usr/bin/msmtpd --interface=127.0.0.1 --port=25 --log=syslog --command='/usr/sbin/dma -f %%F --' Restart=always RestartSec=60 [Install] WantedBy=multi-user.target The inspiration for the --command option is from: https://github.com/computator/smtp-proxy-container/blob/main/entrypoint.sh Thats all. If you consider that this is a corner user case, you can close this bugreport without problem. Many thanks for your work on Debian. Greetings. Martintxo.