block newletter type spam with long url

[24x7server]

hi

we are getting spam with long url links to external websites.

few examples given below

is there any rule to block these ?

basically i need to block any url which contains too many alphanumeric characters at the end.

http://xxxxx.com/uquote/b7e7c7f955d9af8c5efa5d66ea4404d9
http://www.xxxx.us/l/lt1N2743MF255X/719V2211P5437V11AV76246308H3322696621

http://www.xxxxx.us/ait/D2693TE234DJ/648S2030CK5094I11U76246308GB3322696483/wwwc/20218728/vuxtxum_tsom_tt6um_tsn_tt3umv~5tful_tpl_u_uw_ullnrxrsvvyprmp/plmz0qqs_uztdyumplqsmnpprtceumqt7u_ts_m_usrtdfw3yu_f52_f_f_/0_tj_845ktxveunmpnte3yuo_urotcx3yumonlptziaulte3ummm_ut0x0u/t0xut7euqty1u_ttf1u_lmt2utezdeuteutyutw2utv3utvaut0u_98638z/_y9xe9cvezty8uavcx97afezcd_ox97tdy97utd3aut09ultcdautd3uono/lontw3utwv8utweut80utecegutfnutaeut263yutdzeumt9cul_o_ur_t_ttj9vum


thank you,

rajesh