Why Emails with .zip attachments are not received

I am sending a mail with an attachment of zip extension and it is not received at all however the roundcube is alerting me that the mail is sent.

Note: file size is 44KB

unrelated to roundcube (admin will know the answer - if is enabled or filtered)

can you say what’s inside the zip archive?

if you send it to some gmail address
please note that the zip file does not contain any of the blocked extensions

Gmail does not allow you to attach certain types of files, including:

  • Certain file types, including their compressed form (like .gz or .bz2 files) or when found within archives (like .zip or .tgz files)

  • Documents with malicious macros

  • Password protected archives whose content is an archive

File types you can not include as attachments (also in zip)

.AD, .ADP, .BAT, .CHM, .CMD, .COM, .CPL, .DLL, .DMG, .EXE, .HTA, .INS, .ISP, .JAR, .JS, .JSE, .LIB , .LNK, .MDE, .MSC, .MSI, .MSP, .MST, .NSH .PIF, .SCR, .SCT, .SHB, .SYS, .VB, .VBE, .VBS, .VXD, .WSC , .WSF, .WSH