Emails end up in spam folder

[Pumpal]

Hi,

Since recently I started working in a new place where they're using roundcube for their mail and I've noticed that quite a lot of my sent emails end up in the receivers' spam folder. I've even tested it myself and noticed that when I send a mail to my own Gmail-account, I receive it normally, but when I send it to my Hotmail-account, the mail ends up in the spam folder.
Is there anything I can do to resolve this and to make sure that none of my emails go to spam folders, because it's pretty annoying to follow-up each mail which I don't receive an answer to (assuming the receiver didn't read it)..

Thanks in advance,
P.

[JohnDoh]

You need to contact who ever runs your email. Roundcube is an email client. Messages going into spam at the receivers' end is more likely due to your email server rather than your client.